Why would a school prevent reapplying after declining an offer of admission?
I believe the issue here is that if a student has already been offered admission and turned it down, then the school has already given that student due consideration in reviewing the application. Reapplying in the following year means that the candidate was apparently unsatisfied with any of the offers of admission received, which included the school in question. So what would have changed in such a short period of time that meant the offer wasn't good enough then, but is good enough now?