This would explain it.
Bummed though unfortunately not surprised when the rentals disappeared from the Sassagoula River area, bummed and very surprised they had disappeared from Ft Wilderness when we stayed a few nights over there last year, as they fit so well there and always seemed to be popular (not to mention that if you're going to let a bunch of tourists loose in motor boats, Bay Lake would seem to be the best place for it). Looks like the only marina with rentals left on Bay Lake is Contemporary, and beyond that there's only Grand Floridian or Beach Club/Yacht Club.