As a tank, I usually check the party levels before we start to see who's there for what reason. I'll also typically cater the run to maximize experience over the shortest duration. Aurum Vale is a perfect example of this: skip the monsters that can be skipped, while allowing the seedlings to germinate.

Dungeon parties are a balancing act. But when someone (anyone) purposefully pulls additional targets, not only does it upset the careful control of the situation (potentially causing deaths), it also messes up the efficiency I'm trying to maintain. Remember what's important here is the your experience rate, per hour and not per kill.

Like it or not, it's part of the tank's job to determine what should be pulled and when, and it's your job to kill those things. Trust that your tank has a plan that is in the best interests of you and your party. If you can't or won't do that, then you should stick to FATEs.