I agree with having some sort of self-parsing system in place. But not that you can see what others are doing. Do this for DPS and HPS and maybe even damage mitigated (for tanks).
Maybe also have a rating, going from 1 to 10, or D- to S+, when it comes to damage output for your class, compared to everyone else who plays that class in that fight.

Fact is that people will gatekeep if they can see what other people's DPS/HPS is, and that is undesirable. But having some sort of rating, some way to figure out if your own rotation and playstyle is fine and competitive with others, would be good. It's not toxic, it will actually improve everyone's gameplay.

Add in potential tips with "use more AOE skills according to your class" or "manage your gauge better, you were overcapping", or "Remember to apply your DOTs" or "You overhealed a lot, maybe use more damage spells if everyone is healthy!".... stuff like that will be amazing to teach players to play their class and just improve the general game experience for *everyone*, without making it all about optimization.