Theres another point for the "Parsers are bad because it promotes toxicity" angle: Achievements do the same thing. The higher end players will always find some ways to gauge how qualified a player is. In WoW, it was (atleast when I played years ago) achievement linking. You wanted to join a group to run a raid? Link your achieve. This posed even bigger issues than Parsers because completing content is a team effort, so if you were struggling to complete content due to not being able to find a good group, you were SoL. You either had to find a guild or group thatd take the risk with you, or grind through pugs until you got that clear.

Atleast wtih parsers, they can see your damage output and rotations (even on non cleared fights if you choose to upload that information) and give people who want to recruit something to go with. And most people recruiting will ask you about your performances if theyre inconsistent. If they notice you got low numbers, but the tank is dead half hte time, theyre not likely to hold those bad runs against you if it appears you were doing everything fine up till then.

But as I said, if its not parsers, itll be something else. And the more "ambiguous" the rule of measurement, the more toxic and discerning raid groups will get. Raids dont judge you by one single performance; theyll look at you as a whole. So if youre afraid of being seen as "unworthy" than just practice and improve. Wouldnt believe how much of the issue surrounding toxicity in game is down to players just not giving a rats butt about their own performance and making things difficult for other players.