I don't use Healbot. I barely have an understanding of what it is. I checked it out on Curse and as far as I could tell, it's just a healing mod that takes the place of Grid and a couple others.
However, I was reading a guild's application page today and it said "Anyone found running Healbot or similar addons will be removed from the guild without warning." I also have run into a few posts along the lines of "Healbot healers are bad healers" on these and other forums.
So my question is, what's wrong with it? What is it about it that would warrant a gboot or make you a terrible healer?