Guess what chief, there's a difference between being able to do something on a dummy and doing it when it matters, and no, the answer is not always a straight forward "yes." That's just clear as day. You can make excuses all you want and condescend half the community by telling them they don't understand the ability, but the fact remains that 3 out of 4 tanks can be healed to 50% or less HP during an invuln and be perfectly fine whereas one will ALWAYS die at no fault of their own.
Edit - Even if half the community "doesn't understand" an ability, why is that kind of ability in a game that the developers claim to be trying to make more accessible?
Literally the only thing you have to stand on is your elitism and wanting it to be difficult for other players, and frankly I'd respect you a lot more if you just admitted that.