But I find it hard to understand, why you come from: "There was a single group that kicked me, because I was not dpsing and acted really mean." to "The community puts too much pressure on healers and dpsing healers should not be found in general."

I mean, one group =/= the community.
Maybe you should try to find yourself a static instead of going with changing groups? If you find it hard/need more time to learn fights and feel comfortable with mechanics and stance dancing that is totally fine and I am 100% sure there are people out there, who will gladly have you in their group. ^^
But you also have to see that not all people are nice and patient and there are some d***heads out there, who will always tell others off to compensate their own lack of whatever. :/