What are the most common reasons people don't dps?

[Vyriah]

Following that sort of reasoning, playing skillfully is a “bonus” that isn’t strictly required to clear the vast majority of the game’s content. While this happens to be true, it’s a sad way to look at things.

How so ?
What I find sad is saying some one that would come into the this forum and say "I beat NeoExdeath but i'm a bad healer". How in the world ? That's an achievement, be proud of it. And there's still even more room for improvement after that. That's all good things, no drawback, why would someone even be agonizing over want to improve ? That's absurd, that's exactly what the game is about.

Overperforming is litterally just bonus, something you do because you can. That's what is great about it, you don't need it to do it but you still do it because you want to do it. And at some point because you can do it. How's that sad ? That's the best part of learning anything.