Quote Originally Posted by AnotherPerson View Post
Most likely, the actual reason is that when tanks are in need, people queue up for tanks, and then queue gets bloated with tanks but DF takes a while to update the change in the role in need. Still doesn't change the fact that healer queues are practically instant unless you happen to get a bot (which I also noticed has been happening a lot more often lately).
It also looks like it starts a group with a tank and then fills all the other roles. Still, to start a group it waits for a group slot from the instance server so a tank may wait for the instance to be created while healers and DPS are filled into already created instances... or something like that. Did a lot of healers/tanks dungeon roulette spam to notice it. At some points when the instance server is overloaded it can even display some error messages about it and queue will not pop.