Isn't the whole point of a rewards program to reward customers for being loyal and spending more?
No, the point of rewards programs are to try to encourage you to spend only with this company.. and not others.
Hotel rewards programs, casino programs, etc are intended to TRAP your business with them. They have to compete with many different 'like' competitors.. so the programs are designed to create vendor lock where you always come back to them.. for the lure of some benefit or discount.
This is very different from Disney's world. Disney doesn't have a like or equal competitor it's competing with. Disney knows this... Disney's system is not setup to trap your business, but rather simply try to encourage you to come more. They know you want to visit Disney.. the model is simply 'how do I close the deal?' - and they offer discounts to do so.
But an important distinction is in that model you use a discount 'per transaction' to try to close the deal. 'Come between Nov and Dec and get XYZ'. Not 'Hey Mr Bill, you've been a great customer, so here's 20% off going forward for your loyality'
Disney isn't in the loyalty program business.. they are in the "discount to close" the deal business.
As long as Disney doesn't think it has equal competitors fighting for their customers... they don't need a loyalty program. Those people are going to pick Disney anyways.. the key is to pull them more frequently and for bigger spends.
The more often you come tho, the less you have to spend... hence another reason Disney loves the less frequent traveler vs the weekly guy.