IMHO the RCI option holds no value for
DVC owners, you almost always "trade down". So if they removed that for resale owners, I see no actual value removed.
OTOH the more DVC owners who uses the RCI option the more DVC units are deposited into RCI, giving DVC more of the 195$ exchange fee.
Could it instead be that DVC have found that the rental marked is huge and want "their" cut. So maybe they are introducing, some sort of marked place to rent your points. DVC has the option to provide more security for the guests that the other online rental companies can't. DVC could also provide more security for the owners ( at a cost ofc).
You could argue that this would capitalize on their own rental options, but currently DVC is not getting any money for any rentals and are still making money renting.