The only "rule" for want of a better term I find silly is the whole "you spank it, you tank it" mentality. If you asked someone not to pull ahead of you and they continuously do, have at it then. You've at least tried to work with them. However, just outright refusing to pick up mobs because they aggro'd more isn't accomplishing anything. All you have done is given the healer more work. And no, you aren't "teaching them a lesson." Odds are if they're willing to pull for you, they couldn't care less.

It's kind of the same philosophy as purposefully standing in AoEs because the healer isn't DPSing.