Board Thread:Naruto Discussions/@comment-24142271-20141020171924/@comment-1018594-20141020174056

That's just a technique. It isn't always active. Obito managed to kill Konan relatively easily once he caught her off-guard.

Also, keep in mind that this isn't a series of one-on-one battles. Everyone is attacking everyone; blood will be split. Hidan just has to run his tongue across the floor, start his ritual and everyone's dead in a few heart stabs.