Does it really make a difference whether an owner uses their points for themselves, a friend, a family member or a renter?
It can, but probably only at the margins.
If I am speculatively booking for a rental, (and I am not a volume business*), I am going to go after the highest value targets I can possibly find, and doing so as early as I possibly can. In
DVC, the highest-value targets are studios. One easy-to-find rental outlet has 124 reservations for rent listed starting in 1/1/2023 or later. Of those 124 listings, exactly two are not studios: a 1BR Value at AKV (itself a hard target) and a 2BR at the Grand Californian (ditto).
I suppose it is possible that the membership at large is booking studios over larger villas at rate of 60:1 in the 11-7 month window, but I bet it's not very likely. If not, this is an instance where the rental market is skewing booking patterns even more highly in favor of studios than it would have been if owners were just booking for themselves or their friends and family. And that's because studios have much more room for profit than larger units.
But, regardless of whether more owners are spec renting, its part of the program to be able to book rooms with your own points for others to use
That's certainly true, and as I wrote early in the thread, I don't think there is anything DVC can do to put much of a dent in spec renting because most renters are probably small potatoes, and that's nothing more than a game of whack-a-mole.
However, there is a way to make some headway. Some years back Wyndham updated their definition of "commercial use" to include "use by an owner of public advertising or an online website to seek renters". A month or so ago they sent a cease-and-desist letter to at least one owner who listed
one single unit for rent on a Facebook group page using their real name. That owner claims to have rented only that one unit, ever, in many years of ownership. So Wyndham appears to be willing to play whack-a-mole.
DVC has similar, and originally very nebulous, prohibitions against commercial use. In the late '00s they amended it to include a provision that any single Member with 20 or more reservations in a 12-month period would potentially be required to demonstrate they were "not commercial." There is nothing, in principle, preventing Disney from further defining what they might mean by commercial use.
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*: If I am a volume business, I do things a little differently, in that I don't want to tie up a lot of points for a long time, the way spec renting does. But, the 20-reservation-rule probably makes volume businesses hard, and the economics of it doesn't make much sense anyway because the DVC cost basis is so high.