I mean let's do a mental exercise, do you think generally abandon groups for the right reasons or the wrong ones? If you think they do it for the right reasons, then fine there's no reason to have penalty. If you think they do it for the wrong reasons, well that's the reason for a penalty. I think the penalty in the long run is probably a good idea, since I doubt the majority of people who get truly horrible groups mind eating it to get out of there.