My theory is it's parser influenced brainrot.

Since a DPS's entire job is to maximize their damage as is, it just create a mindset that they *must* be at their best in any fight. And if they can't for one reason or another, they must make their party think they are because, again, a DPS's entire job is to maximize their damage and not doing so is both a personal failure and a team failure. Also, you must be a team player and help the DPS do their job at peak play or you are failing them.

Meanwhile just not sucking and completing the content with being dick to each other is the actual only goal.