because the perception will prevent most gym hopping and the hoops you have to jump through. 99% of gym hopping is bad. and if someone really felt that strongly against it they would test he system in the faults i have mentioned. raise a big stink about it, and the system would adjust. now, they would pretty much black list themselves because what gym wants to deal with an individual who will willingly make political statements, but they would make a point.
and honestly this rule highly helps good businesses. because all decisions need to be made on a year long basis (or is the perception and this rule is even perceived to affect kids all the way down to mini 1... for what reason i have no idea) it means they will choose stronger more solid businesses that look like they will be around all year long.