Welcome.
The rooms you see available on CRO - including the ones available with an AP discount - are USUALLY the rooms that have been traded out by a
DVC member for the member to do something else - for instance cruise - then DVC sells that room in order to pay for it. I think the best way to think of these is that a DVC member is staying in them - they are just staying in them in the middle of the Carribean.
There are other ways these rooms are available for cash, like a room count based off the points that members don't own because they haven't been sold yet, or have been for closed on, or the member didn't pay dues. But it isn't the "more money" thing - members are entitled to rooms owned by members, Disney doesn't get to just take them.
Now WHICH rooms at WHICH times Disney puts into the CRO pool is a huge mystery. They do need to try and pick rooms that are likely to sell, otherwise they can't pay for those exchanges and then the cost in points for exchanges increases. But how this happens isn't transparent.