I assume that everybody who "fails" at playing a rogue follows a particular mindset. "This is a dps class! I do dps! let's go!"-mindset. That is inefficient above casual difficulty. I also assume those who "fail" also doesn't plan their build, or team. Basically, they play they don't play optimized, nor do they play on their classes strength.
Let's break it down:
A rogue is:
not a tank.
not meant to take damage.
not meant to stand in the open
not meant to focus the tanks
not meant to be a hybrid between range and melee
A rogue is meant to:
Take down priority targets. (Ranger > Mages >>>>>>> Warrior w/o shield > Warrior with shield >> Maulers)
Position themself. You avoid damage, and gain, damage by stealthing. use it. You position yourself.
If your playstyle consist of "I SEE **** LETS KILL LOLOLO", you are picking the wrong class. Rogues build on strategy and priority. You are not the first to engage, nor are you going to be attacking constantly. You stealth, wait for your tank to poke the group and you pick your target. See 3 archers up there? Go behind one of them. Twin Fangs him. A few melee hit for good measure, and end in Deathblow. If possible, re-stealth (assassination specalization) and do the same for the next archer, then the third one. Let your party take care of that mauler. You have no business dealing with Guard when there are archers up.
Once you get the hang of the rogues playstyle, their damage is unmatched. Tempest popping fire flask when a boss is under 50%? Spam Deathblow for thousand upon thousand of damage. See a big dragon? Pop Deathmark, stealth, do youre combo and watch the dragon losing another 25k-70k damage.
See a pesky enemy with a bit too much health? Death mark --> stealth --> poison weapon --> Twin fangs --> Deathblow --> Hidden Blades --> Watch him explode.
Re-stealth and repeat.
My point: If you get hit, regular, as a rogue you are playing the wrong class. Warrior is your class, and even then you are playing wrong. If you are rushing into things with no mind of what target to choose, you are playing it wrong. If you favor lots of AoE and just smash your face into groups of enemies -- you are playing the wrong class.
Rogue favors the quick, the decision-makers, the priority-based-people and the one living for High risk/High reward playstyle. it favors the min/maxer, the optimizer and the one looking for a challenge. As a rogue you rely on your instinct, and on your teams setup. Fail either, and you are dead. Get both right, and you will roll over the content on nightmare.