Some people won't ever get better. Those people are casuals. Sometimes those casuals are both ignorant and jealous enough to deny other people have skill since they themselves have none.
Some people will get better. Some people will reach a plateau sooner or later. Some people will break that plateau into bits, and reach ever higher levels of mastery, sometimes progressively, sometimes in spurts of inspiration.
I like people in the latter category, always willing to learn and actually get better.
don't even need to aim for "headshots" or anything similar.
Typical sign of ignorance demonstrated here.
Just a few things to learn, not a comprehensive list,
Flanking attacks (bonus damage), Setting up Combos / Detonating combos huge bonus damage (both ME3 and DAI technically don't have to, but you're a noob if you aren't aware of these), Timing of knockdowns, enemy animations (Important in avoiding sync kills in ME3 for one, DAI avoiding enemy arrow fire, and engaging despair demons as melee for two),
There's plenty to learn, but is it obvious, nope. Enemy weakpoints were only a tiny fraction of what you needed to learn in ME3, and the same goes for DAMP.
The same kit will always do more damage, avoid more damage and generally excel better in the hands of a more skilled player, aware of their abilities, their enemies, their surroundings, and their teammates. If you play exclusively pugs, that's your choice to play around terrible people instead of getting a headset, and making friends & private games instead of lack of teammates in pugs.
There's definitely skills in this game, and there's definitely people with it, and without it. On BSN, there's people without skill complaining about the people with skill.