Like I said in my previous post. Many healers resist the thought of having to do something other than heal. The guy, Tyven(?), I think his name is encapsulates this perfectly.
It's the same as DPS & Tanks. If they aren't able to time personals/mitigate damage using whatever tools they have available I wouldn't play with them in the same way a healer standing overhealing or full on idle while nobody takes damage is just a trash individual.