>>714437642Because even in actual savage content Tanks are more than likely going to be the last to die. Any damage that needs to be mitigated can be handled by rampart itself, you aren't gonna need to save it for some else.
The only situation I can think of where it'd actually help would be M6S, and that is assuming you can stack enough to make two yans more survivable with less attention needed from the healers while not losing so much damage that you can't decently whittle down one of the Yans by yourself.
In any other form of content the tank is only dying if the tank does something horribly wrong or, occasionally, because a healer didn't heal when they should have.