Always another side to the story, always.
Source : M+ keys leaver right here.
You say tank left cuz the grp wasn’t going to 3 chest it.
I say I left because it was going to take 1 hour and I didn’t sign up for that.
You say someone left after their mistake was pointed out.
I say someone was being awfully rude to me.
You say some one left because they didn’t like the group’s performance.
I say I left because the group turned out not what they advertised and I don’t wanna get scammed into boosting people who don’t deserve it.
and the loop goes on and on and on.
M+ leaving issue is a case by case issue.
Sometimes the leaver is in the right side, sometimes the leaver is in the wrong.
If blizzard choose one side then the other will be unfairly treated and will complain, quit , take extreme measures.
And blizzard can’t realistically have people that study M+ leavers case by case.
Now on to another subject that might interest you OP, we have a community that is trying to bring back the social aspect of the game, it’s open for everyone regardless of what they like in the game with hopes of making the game more social and maybe if people wanted they could group up with others in the community.
You can find Mythic raiders, old content players, High Rio players and people who just do M+0s, no one differentiates or speaks lowly to others, if it interests you feel free to join, I’m pretty sure you won’t find douches in here like the tank you mentioned in your OP.
Here’s the link to the community :-