There was a time when a friend (SCH) and I (NIN) used party finder and got stuck with a tank that refused to turn on tank stance and threatened to not heal me if I move too much (the aggro was constantly on me and this makes no sense at all since he's not the healer to begin with and I have a habit of moving to reposition my attacks) and a DPS who kept trash talking the healer and complaining about not getting enough heals when his health never came close to dropping below 50%. That group was complete cancer.

This was the first and only time I ever left a party finder group and nobody can blame me for wanting to leave that. Doubling is too strict if you don't know the full circumstances behind why someone left (especially if it's a real life emergency). A 30 minute punishment is about right.