If you call up
DVC and ask to buy a contract at a sold-out resort, they can only sell you those points they have in inventory, typically acquired through ROFR, foreclosure, surrender, etc..
The problem is, the points come back in as they went out: in the tiny chunks that make up individual contracts. Depending on when those contracts were originally sold, the points could be from any of the units the resort is divided up into, or many of them.
For DVC to sell you that contract you want, let’s say it’s 300 points at BCV, all 300 of those points need to be from the same unit number. If DVC doesn’t have 300 points allocated to the same unit number, they can’t sell you the 300 points.
DVC can change the use year of points, but they cannot change the unit those points are allocated to. To get you the 300 points you want to buy, DVC has to find them. One suggested use of ROFR, is for DVC to take back points from a specific unit number, in order to be able to sell larger contracts at sold-out resorts (which always carry a HUGE markup when buying direct).