For the most part I don't need a damage meter to feel when something is off in a party since things would be taking longer to kill than usual. That being said for people who prioritize high end content, even if they ban ACT Yoship said it himself that raiders will take out a calculator and start adding up damage manually by using the info displayed in the combat log like in the olden days.

WoW players are not boogiemen to be afraid of. If you're getting called out for not dealing enough damage, something would seriously have to have gone wrong like a dancer using their steps while being miles away from the enemies or a healer refusing to dps at all in a dungeon run. Otherwise, it would be difficult to notice that anything unusual is happening. Oftentimes these are easy fixes and it's not difficult to suggest ways to improve in a helpful manner rather than a toxic one.