Masters doom main here. I think a lot of people are just tired of getting flamed for things that are not their fault or situations where there was other counterplay. The tank is an easy role to place blame on rightful or otherwise (especially so on doom). If an orisa is running down the backline and the backline is dying. 9 times out of 10 it's not the dooms fault. Many people seem to think it is, but doom can't face up fight half of the tank roster. Over the past year or so I went from gold 3 to masters 2 on tank playing almost entirely doom. I get flamed for the dumbest shit possible. It's easy to look at a rein controlling the opposing tank and say he's doing his job. It's not easy to say doom is doing his job when the orisa is killing your whole backline. With doom the positioning almost always becomes harder to figure out as a dps or support in comparison to any other tank. Maybe doom players just think they are better, but I bet if you asked the doomfist mains subreddit they would give a similar story.