I think the community as a whole often times labels casuals instantly as bad players.
They claim "Doesn't improve or won't" as a reason. Like half the posts here, but their definition of improving differs from the other players definition.
I've been yelled at and harassed as a healer for not doing enough damage. I was yelled at by tanks for keeping them at full health. That's not improving myself. It's not making be better as I want to be better. When I play a healer, I do just that, play a healer. I loathe magic damage with a very firm passion. My overall least favorite anything in the game.
As a tank, which I've stopped doing, I don't know most dungeons. I don't tell people either. Why? Because going into a dungeon you're forced to do at 58 and saying you've never been here and don't know anything about it just means half the group will leave instantly.
This community thinks that they're the greatest in MMO gaming, but they're not. They're in fact, worse than other mmo's. Because only in this game do tanks and healers get harassed for lack of damage in addition to their core role.