Why do people hate on tanky healers?

[Assirra]

Your skill would prevent u from running out of mp.
But if u do run out of mp after doing everything u could ( i.e using potions, conserving mp/ timing shroud, utilizing free cure etc. ) then that isn't ur fault and not really a problem on ur end. Cuz its either that people were taking too many unnecessary hits or the fight was dragged out longer than it should have. Or the worse, having to raise a couple of people because they died to something dodgeable.

Or because you don't have enough mind and you need to cast more spells to get the same results than other healers resulting in to you being out of mana. And because your heals aren't effective enough, the other healer needs to carry more of the group then intended so he runs out of mana faster as well.
Its easy to shift the blame but from the start you are already gimping yourself because you want to be more tanky.