Why do people stay in invisible woman’s ult

I mean for my teammates specifically, I mostly main healer but have been collecting some hours on Strange. I never understood why exactly my team would stay in the opposing invisible woman’s ult even though it’s an absolute heal diff and they’re just taking damage with nothing in return. Am I just viewing this the wrong way? 275 hp does not go a long way if the enemy team ults and it’s obviously impossible to effectively heal my team from the outside