The biggest problem is actually none of these, but the general apathy and ignorance that tends to exist. People don't know / care about how to actually play through the modes and strategize properly. They're there for the XP.

I've been in groups with a handful of these so-called OP classes and we still lose.

I regularly play scholar and there are times I can get some good battle high going as people just don't seem to have their heal button handy, but I'll also have a target on my back from all the fear mongering