Probably because everyone who "quits" is still showing up in game, plus the other characters they have been trying to sign on with as well.
I am so upset!! On Sunday mornings I wake up EARLY to be able to do this quest, then spend hours trying to log in...do you think it is just that so many people are trying to use it that VMK breaks? I really liked when the weekly quests were Thursday evenings...
Awww...I really wanted the prizes, I wasn't able to do the quest for these prizes at the beginning of the month for this same reason, so I was really excited when I saw the prizes, but I froze most of the way through JC and now can't load any rooms in adventureland. Oh well. It would be nice if they extended after these problems...but maybe they dont' know about the problems? Maybe it only seems to get "fixed" just after the quest ends because that's when people stop trying to get in and so VMK stops having an overload?