Not to beat a dead horse but the reservation in question was management controlled, and therefore as you put it "they are entitled to assign the accompanying usage to whomever they want". That is what they did. They either owned or were the legal administrator of the reservation. In assigning usage to "whomever they" wanted they also assigned the unit that they wanted. They did what they wanted which was in their legal right but in doing so they really ticked a paying customer off.
I understand what you are saying, but you slightly change what I referred to. My only point is that the underlying "rights" of an owner to occupancy should be freely assignable. While "they", in your example above, assigned the usage, the controversy is over what particular unit is assigned for that usage. I don't agree that "they" as the owner, can "assign[] the unit that they wanted."
The assignment of particular units, or "priority", should be done by the HOA (or its agent, Marriott as manager), in a manner that treats all owners (and any who are assigned the owner's rights), in an equal fashion.
Is there anything anyone can do if they don't? Not easy, unless owners want to get together and try to fight it. Despite personally having the ability to do so, I've never felt sufficiently pushed down in priority to justify such a fight.
I am confident, based upon conversations with Marriott management, that they are aware of the conflicts between all of the various governing docs (and state laws) and their "timeshare system" (a legal fiction). I also believe that this is the motivation for the DC system: to systematically encourage owners to contractually give up rights (see voting etc.), or establish through trust ownership a system that is based upon contract and not title/governing docs.
In other words, a reversal of the long lived Marriott mantra of "deeded ownership," (and all the pesky obligations this imposes on Marriott.)