Some people don't seen to realize that tanking is not faceroll in this game. There are situations where as a DPS you should actually stop and think a little before going all out on every target. If tank pulls a group of 4 and starts off by using aoe abilities, the DPS are likely to pull threat on main target. If the tank starts off using single target abilities, the healer is likely to pull threat from all the other ones. With a 2.5 second GCD and no consistent taunt it is difficult to gather up targets once they break off from initial pull, don't assume tanks can just instantly pull enemies off of you.