But you said she's "easily the most helpless character in Mass Effect history", when... She's not. At all. She needs help a few times, but all but one of those times are optional and she accomplishes it all anyway, without Shepard. The only thing she doesn't accomplish is saving Feron, and that's not just because Shepard isn't in her party.
No I didn't, I said "possibly". Here's the quote. No, I didn't edit it.
Errr, what?
Liara is possibly the most helpless female in Mass Effect history.
'Possibly' indicates I'm open to the argument that she's not. Which, if you want to include the likes of... Conrad Verner and Kelly Chambers and the traumatized dock worker, I can grant you. But although I didn't specify, I was talking about party members. Regardless, it doesn't matter to the overall point that Liara is helpless at times, and relies on the player for aid. Why did Feron die then, if it had nothing to do with Shepard?
The "assistance of Commander Shepard" isn't just that, though, is it? It's the assistance of the best stealth ship in the galaxy, equipped with the most state of the art equipment in the galaxy, and with a crew comprised of some of the most powerful individuals from every race. And the missing variable isn't Commander Shepard's assistance alone - it's the Cerberus intel. If you remember, the whole thing that sparked it off was Shepard showing up and said "let me help you - here is intel on the location of the base from Cerberus, let me help", and Liara took the opportunity.
Cerberus intel which would never have been researched without Shepard's presence, a ship which would never have been rebuilt without Shepard's presence, a crew which would never have been recruited without Shepard's presence... you could interrupt here with "but Shepard wouldn't even be there in ME2 without Liara." Also true... however, Liara would still be in the mine on Therum without Shepard. The point still stands that without Shepard's individual choice to share the intel combined with his vital assistance against the Shadow Broker, Feron is dead and the rescue mission is not a rescue mission.
If Shepard just showed up on her own and said "let me help", Liara would still need to locate the base on her own, and would still need to figure out how to get there. Liara was also the one who headed to her contact first, she was the one who escaped Tela Vasir's assassination, and she was the one who chased Tela Vasir down afterward, and she also played a huge role in killing the Shadow Broker himself, which Shepard couldn't have done on her own. All proactive things for Liara to be doing. She didn't just sit around in Shepard's shadow as she did all the work for her.
Before the DLC was released, Shepard DOES show up and offer to help. Liara refuses it. Bad move since it cost Feron's life in my playthrough completed before LotSB came out. If she'd said yes, the resourceful Commander could have done any number of things to track down the Shadow Broker but we'll never know what they are because she said no.
As stated multiple times already, no one's denying Liara is a strong and effective and useful character. My initial post was a direct contradiction to Kappa Neko's assertion that Liara inherently comes packaged as THE ideal hero when it's simply not true, unless maybe you skip Mass Effect 1 & 2.
Without the intel from Cerberus, it may have taken her longer to figure out, taken her more time to recruit the necessary. She needed to recruit mercs skilled enough to take on the base with her - that takes time. She needed to find a way to do all of this without alerting the Shadow Broker himself - again, this takes time. It might've been these delays that meant she was too late to reach Feron, and therefore it was too late to save him.
A key word in there is "may have". We simply don't know anything other than that the mission went off successfully with the aid of Shepard, and yes Cerberus and the valiant Normandy crew. It hardly matters who the help is coming from to disprove the notion that Liara is entirely self-reliant.
I'll also note that all of the personal quests in ME1, ME2, and ME3 required Shepard's assistance to solve. Does that make them all "the most helpless character[s] in Mass Effect history"? Miranda can't save her sister without Shepard. Jacob doesn't find his father without Shepard. Garrus won't kill Sidonis without Shepard, and Zaeed wouldn't have killed Vido without Shepard. Samara couldn't capture Morinth without Shepard. Kasumi wouldn't have gotten Keiji's greybox without Shepard. Are they all helpless, too? The galaxy would've been destroyed by the Reapers if it weren't for Shepard. Is the entire galaxy helpless?
First, see the response to AlanC9. Second, each of the cases you mention are individual cases and their importance to each character can be argued. For instance, Garrus can survive the suicide mission whether he does the Sidonis mission or not and the shooting of the coward is hardly essential to Garrus' future.
And uh, yeah, the entire galaxy is rather helpless considering all it took to destroy the Reapers was a pistol. I'd be pretty disappointed to learn that our outer-space neighbors wouldn't have anything better to offer than the largely self-interested/worthless/stupid races who need one Spectre to personally help them all out before they contribute, especially those pathetic asari (that's not a shot at Liara, just her species. Liara is cool).
Heck, Tali's life needed to be saved twice, on Freedom's Progress and again on Haestrom, and then her personal quest involves her having to be saved by Shepard again or she'll be exiled from the Migrant Fleet. Tali is by far my favourite character, but just in ME2 alone she needs to be saved more than Liara does in the entire series. She also needs to be saved from Saren's goons in ME1 when recruiting her.
Arguably, Tali's life didn't need saving on Freedom's Progress but whatever... separate debate from the one about Liara, begun here:
Of course the only "perfect" partner and ideal relationship was Liara. No drama, full support. Bioware tried to teach us all a valuable lesson with Liara (not kidding).
Some of the male characters come close. But none are as determined, passionate and strong as Liara and Cassandra. What sets them apart from the rest is that they don't need your help. They are not broken, don't need babysitting so they don't screw up. They have their insecurities and doubts, especially Cassandra. But their flaws are not the kind of flaws Anders or Solas have.
Like I said, Liara is frustrated by what she feels to be her incompetence compared to what Shepard has accomplished on her own. Shepard saved her life on Therum, and she's helping Liara again now, and Liara can't seem to return the favour. Her expressing insecurity about her usefulness does not make her helpless. Garrus expresses doubts about himself and his handling of multiple situations across the trilogy as well - why isn't he considered helpless? What about Kaidan? He's feeling incompetent and helpless and doesn't feel like he can live up to being a Spectre. Does this mean he's helpless, too? You also have to save him from Eva Core after she basically smashes his skull.
So what exactly would you call Liara in this situation, if not "helpless"?
Her very first line is in fact: "Can you hear me out there? I'm trapped, I need help!" First impressions are pretty significant. I feel her insecurities stem from this point onward and she feels she needs to make up for it subconsciously. It's part of her arc. If she'd never been helpless, she may well have never evolved into the effective companion she becomes. Yep, Kaidan could certainly be defined as helpless a few times in ME3, same as his counterpart, Ashley. Garrus, not as much. Maybe when the drop ship shoots him in the face in ME2.
And omg, the Turians are a heavily militarised society. It's stated numerous times in-game and in-codex that the Turians are constantly preparing for war, and that their entire culture is centred around being a huge and powerful armed force. Even then, they were taken by surprise and are being decimated, hence needing the Krogan support. Asari have been referenced constantly as a diplomatic and artistic race that specialise in subterfuge rather than outright conflict, and all of these skills are useless against the Reapers.
(I would also argue that appropriately applied diplomacy and subterfuge are definitely effective against the Reapers)
Did you not watch the scene where Thessia was destroyed? Reapers were landing everywhere on the planet with Lieutenant Kurin screaming for help before she died, whereas you landed on Menae for Palaven and weren't seeing the devastation there first hand. Plus, just moments before, she found out that the Asari government had been hiding a Prothean beacon from the rest of the universe, and her entire religion and the culture that sprung from it was a lie.
It's also stated in dialogue with Hackett pre-Thessia and with others throughout the ME series that the asari are supposedly the "most powerful" race in the galaxy. The asari ship, the Destiny Ascension is allegedly the strongest in the fleet, indicating that the asari ought to know how to fight a war. So you claim the asari specialize in diplomacy... then why were they less capable here than the turians and krogan as well? The primarch and councillor both show an ability to negotiate and deal directly with their old enemies in order to save each other. Meanwhile, the asari (who have had the most time to prepare AND the most time to evolve) ignore the rest of the galaxy and set themselves up for miserable failure. Instead of holding the asari leaders accountable, the whole invasion of Thessia is treated as some great tragedy and failure on the player's part when the truth is... the asari brought it on themselves in more ways than one. I pity Liara but it's also a bit annoying how she acts like Thessia is the only planet getting totally blitzed. "Maybe the next time we go to war, the Alliance can spring for air support." 
I think seeing the rape of Palaven second-hand is just as effective as showing how totally effed that planet is. Being on the surface of Thessia never revealed that level of destruction. Same with Earth, on which we do get to see the knackered surface. Hearing the audio of an ineffective Lieutenant and some of her soldiers getting glassed didn't really compare to seeing this with Garrus pointing out where he was born.

Anyway, it was fun to slam the silly asari, but this is getting way off topic. I think your post is partially a sensitive reaction to what you perceived as an attack on a character you like and I can assure you that it's not. I
Liara and her character transformation is possibly the best in the series.