So It's against the rules to need for another job?....

[Thaliss]

That many people "Play by MY rules!"...

Calling people selfish or what not. You don't know playtime of other peoples, goals...

In a random instanced group you accept the system the GAME (not you) set in place.

Edit : I don't agree with setting rules in a random group once in an instance even before 1st pull, because this leads to bullying, specially if people setting rules are friends and/or tank/heal.
And I always saw tank/heal asking some lots not the dps (and i play heal/tank as main)