You just reminded me, Guild Wars was full of....children. I'll call them that regardless of their age, because that's how they were acting. Although I enjoyed the mechanics of the game, it got to the point where I said enough was enough and left them to bicker amongst themselves.
Rude and obnoxious seems to be common place for some people on the internet, likely due to the anonymity and lack of serious consequences.
It's not just online video games, although it's quite pronounced there. You'll also find it in various forums of all types. ****ing matches, if you will and all sorts of miscommunication.
I'm not sure what the solution is other than ignore it, quit the game and find a great single player game, play with friends, whichever floats your boat.
I can only speak for myself, but it's a bit of a love/hate relationship with multiplayer games.
Currently, I'm enjoying Serious Sam 3 for the single player aspect, and also a bit of multiplayer, mainly because there's no real reason for anyone to get mad at each other. Just run around, collect weapons and shoot monsters. Simple, yet incredibly fun and challenging to boot.