I have made my peace with this. Because meters are not allowed, apathetically bad players can hide as DPS. They are not subject to the same standards as tanks or healers. It isn't going to change, insulting them or even offering advice can shut them down and make it even worse. Going off on a tirade just makes you the villain and getting that upset is not worth it. You get a hint you are grouping with that just leave, nothing is worth getting that aggravated over. That policy will cause you to leave few people who don't deserve it but you have to do what you have to do to stay sane.