That might be a really good topic for spinning off a new thread!
I can add a data point from my other points-based timeshare, Worldmark the Club (WMtC or simply WM). As a club, WM started roughly the same time as DVC but without designating a home resort or having ending/expiration dates. They made serious changes in 2006, after their developer unit was taken over by Wyndham, to "curb the resale problem."
Basic nature of the new 2006 Developer sales plan, "Worldmark with TravelShare!":
Create a new club-layer that wraps around the existing club. The new club layer ("TravelShare") offers certain exchange benefits that have been stripped from the post-2006 resale transactions and some new benefits ("free" corporate-level RCI membership, special concierge travel services, etc.). The new benefits layer also introduces tiered benefits based on the number of qualified points owned.
The new club layer has its own MF structure added on top of the core club dues. (So new developer contracts pay two distinct dues: one for the core club and one for the new benefits layer.) The new layer can only be obtained through developer sales and does not transfer in resale.
Post 2006 for existing owners: All existing owners were grandfathered to maintain all existing "exchange" rights across the current affiliations. That is, as an owner, I maintained my right to book any WMtC location, any WM South Pacific location (a different but related system servicing South Pacific), any Vacation International location (an outside club with which WM had formed a direct exchange affiliation), etc. I maintain my right to enroll my WM points in exchange systems including RCI and/or II at 'individual responsibility' levels of membership. I don't really lose anything ... but do not gain any of the new TravelShare benefits unless I choose to "upgrade" my account with a minimum add-on purchase of new points under the new plan. Similar to DVC, all points owned are tagged with an attribute designating their qualification status ("WM+A," reflecting Worldmark plus Affiliations). FWIW, WM+A points are eligible for an "upgrade" ($$$) to new 2006+ developer point status. If I sell my points, they lose their "+A" status.
Post 2006 for new resale transactions: Resale points are tagged "WM" and may book all core WMtC property inventory but are ineligible for reservations requiring a newly coined "The Exchange Network (TEN)" system of managing affiliations. Thus, resale could not "exchange" to WM South Pacific locations and are not eligible for exchange to Wyndham properties (a feature added after the 2006 changes; not sure if resale may book Vacation International locations??) We are told post-2006 resale points are ineligible for "upgrade" ($$$) to the new 2006+ developer point status. (Not sure if this is truly enforced at the sales table.)
Post 2006 Developer sales: New developer sales include both the core club (WM) and the new TravelShare (TS) benefits layer: WM+TS. The owner pays
extra dues and receive their "free" RCI membership through TravelShare, access to multiple direct-exchange affiliations (WM<>WM South Pacific, WM<>Wyndham, etc.), a dedicated phone line for reservations, invitations to special TravelShare events, special check-in lines at each resort (based on new tiered membership levels), etc.
Lots of pressure is added based on your new "tiered membership level," oh, my!
When an owners of "WM+TS" sell their account it is tripped of "+TS" and becomes simply "WM" and the resulting resale owner pays only the core club dues.
FWIW, we've owned WM since 2000. Our contract originated in 1990 and has lots of grandfathered features. We don't plan to either sell it or upgrade. We quit entertaining thoughts of increasing our account size soon after review of the 2006 changes. So the changes basically put us into "hunker down" state. We've been OK.
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EDITED TO ADD: One curious outcome of the 2006+ changes has been a completely confusing Resort Map. Every location is color coded and ties to the following legend:
My account (WM+A) is eligible for all
except for the bright green "Wyndham Hotels and Resorts (TravelShare members only)." A basic WM account (lacking +A or +TS) is eligible for the Red dot locations only, I believe, but
might also receive the darkest Purple dot affiliates.
The colorful resort map sure makes a powerful statement at the developer sales table: "You want
all these locations right? Gotta buy from me, today."