The 'unwritten rule' for non-tank pulls in dungeons

[linay]

As I've said before, it's not about what's fastest or most efficient-- efficiency is often the death of fun, anyway. It's about getting rid of an undesirable from your group, and you all agreeing to stick together to the end. Without that undesirable, just because you can.

Then what makes the tank undesirable?

On another note, I've seen many tanks pull one at a time at both leveling and expert dungeons without seeing any vote to kick prompt, so I think the idea that those tanks should get kicked is actually shared by a minority of people. The only one time someone disagrees, they actually left on their own without even prompting a vote.