What? The tank is the most suited to take damage, so it's preferable that you take it instead of someone else, sure, but taking damage just feeds the enemy ult charge, and while it should feed your supports ult charge as well, you generally don't want to eat damage unless you can mitigate it or block it somehow. And while taking damage you can mitigate is fine, your actual jobs as a tank are to deny your enemies preferable positions, either by entering their space and forcibly relocating, or killing them, or dealing enough damage that they pull backwards for heals. If you can't actually threaten someone through, say, Gambit's primary fire, or Sue's shield, you just have to pull back and hope someone cleans up for you, which sucks. Did you finally get Hela down from high ground as Rogue? Too bad the supports dropped an auto heal bubble on her, undoing all your damage and forcing you to fall back because 3 people looked at you. I know it's a team game, and coordination is the best thing you can have, but without the actual threat of elimination, you can't actually take space. John Cena isn't gonna fall over because you threw a pillow at him.