It seems like it would be the other way around if they were trying to lower/remove operating expense for those "combined" DVC/hotel resorts... It seems Disney would bill DVC, which in turn covers those expenses directly with MF's.
That would:
1. Greatly lower Disney's "resorts divsion" expenses to operate the hotels, directly tying those costs to income (the bill to DVC).
2. Allows DVC to directly tie the expenses they're billed for at the combination resorts to the members via MF's (maybe at a profit?).
If your customer base is paying for the vast majority of expenses to run resorts directly, then a higher percentage from tickets, meals, resort services, etc, goes directly to the bottom line.
There are rules and laws governing MF's and how they have to be laid out, etc... There aren't rules like that for what they do with the other revenue they bring in. That's why I wonder if they do it this way. Follow the letter of the law on the MF's but load expenses in to the fullest extent possible, even covering "shared" resort expenses... Which allows freedom to do as they please with the other revenue they bring in, because nobody is privvy to what they do with that.