There is an absolutely HUGE laundry list of tanks out there that simply do not know how to keep hate on mob groups so if you spam heal, say, cure 1 you will take hate quite easily..

Also NEVER cast regen on tank while not fighting and NEVER stoneskin just before he is about to pull. THese will give you immediate hate.

All in all there are just a lot of terribad tanks out there that dont know how to do their role plain and simple and we need to be careful with our heals to prevent from gaining too much hate.. Its funny you are actually being blamed for their incompetence but it is what it is. Just wait till their health is 75% before tossing out heals and dont spam cure 2