Healers that only heal usually can't keep a tank alive through a big pull or huge damage burst. Proven time and time and time and time and time and time and time and time and again.

As an Omni-Role Player (who has mained a healer since 2.0 came out early access) I speak from personal experience.

Healers only flew back in original ARR because we didn't have the Mp or Ogcd's to do it full time on White Mage.

If you only heal, you're really just being stubborn and prideful.

But hey, "I don't pay your sub." So yea, rock on I guess?