Too many people in this thread are blaming noobs for being treated badly and saying what they should differently. Stop blaming the victims. They're noobs. They don't know anything. They don't even know they could say they're new. They just know they're being yelled at and not having fun.

Yelling at someone is one of the most useless things you can do. People don't respond well to being yelled at by strangers so it almost never fixes the problem. When you yell at people, you're acting like a noob who doesn't know how to game.

If you want to succeed, be patient and offer some advice. If someone is trying to tank or heal, then be especially patient with them. Why? Check out the long dps queue, that's why. Every time you help a new tank or healer stick around, it helps reduce the queue. Telling someone to give up or play dps simply increases queue length.