I don't ever recall reading this anywhere but crossed my mind the other day.
Does Fastpass+ or at least what we know about FP+ remind anyone of the old ticket books from the 70s? Although I have never used either it strikes me as being the same kind of concept. Certain number of passes or tickets per level of attraction.
Obviously now if you run out of FP+ you can still ride every other ride as much as you would like.