Isn't there a use-it-or-lose-it deadline in any Points system? I would think there would have to be, because otherwise owners could stockpile from year to year and thoroughly mess up the inventory controls. I'll admit I only know the rules in two Points systems - Marriott's and DVC's - and in both of those you have to either use your Points in their Use Year or bank them into the following year by a certain date. Theoretically, if banking was allowed indefinitely, couldn't a situation arise where there are not enough accommodations for the number of owners who have usage in a certain year?
The 800 bonus Points given as an enrollment incentive have more restrictions on usage than the Points you get from converting an enrolled Week. Bonus Points can't be banked or transferred to another owner, so yes, if you don't manage them carefully then you'll lose however many are "orphaned." You could call that a form of skim, I guess, but the owner didn't actually pay a per-Point fee for them. They're a one-time incentive and if I lost them because of the expiration rules, it would be difficult for me to think that Marriott "cheated" me out of something. At least not in the way that most TUGgers say they feel cheated by the skim that exists when a Points allotment is not enough to book the same Week given up for the Points.
Those types of Points have more usage options than the one-time Bonus Points, in that they can be banked into the next year or transferred in a private transaction to another DC Points enrollee/owner. Or a reservation made with them could be rented to anyone. Granted, there are still deadlines for using them and if you don't manage to use all of them you will eventually lose them. But that responsibility for managing them falls on the owner, not on Marriott. That's why I say that if you want to call such loss a skim it makes a certain sense but IMO it's not similar to the built-in skim that occurs with a majority of Marriott Weeks, which automatically gives Marriott value each time an enrollee converts those certain Weeks to Points.
It really all comes down to, in both Points and Weeks systems owners stand to lose usage if they do not manage the ownership according to the rules. Points systems allow more of the "orphan" situations because Points can be broken up for single-day use, and Points requirements for stays may not be uniform across all resorts within a system. (Which, they're not uniform in both Marriott's and Disney's systems.) But I've also learned reading TUG that there are a certain percentage of timeshare owners who do not use their ownership at all, so obviously plenty of Weeks go un-used too.
If we call those situations "skim" then I guess we have to call non-usage of any Points "skim" as well. But the "blame" (if that's the correct word and I'm not sure it is) for this new form of skim lies with the owner who didn't use them, and not with Marriott. If the owner manages every Point allotted according to the rules, just like with Weeks, Marriott has no way of taking added value from them.