Dude. When you do group content, there's a social contract. I respect your time, and you respect mine. Sure, there are both toxic and non-toxic ways of dealing with a situation where somebody else is wasting your fucking time, but ultimately what's toxic and bullshit on its face is when people don't take the time to understand what they're supposed to do in M+ runs, fuck the key up for 4 other people, and are so entitled as to think that everyone else is the problem for taking issue with that.
I have no problem with people being shit at the game. It happens. I do have a problem when people don't have the humility to own their shit and try to learn from it. It's a shit attitude, and it's why certain players never improve. There's much less toxicity in groups where everyone is at the top of their game, because those people have a positive mentality when it comes to introspection and self-improvement.