Technically, that's the rule both HS and college. One reason to do it that way is because if high seeds don't get pigtails they lose a chance at bonus points. It does become an issue when events decide to seed all the way down forcing high seeds to get byes. It might not be a problem in, say, the current EIWA with only one pigtail and most of them going to a lot of the same few lower ranked teams.