Every timeshare is limited by law to selling only the number of room-nights each resort has -- you can't sell gullible timeshare marks something which does not exist. In DVC's case that means a specific number of points per Use Year
Looking at a particular Use Year, your points represent a specific buying power for accommodations for that year. Yes, they are your points -- and yes, you have paid the MFs for those points -- but only for that year.
To say "I paid for those points so I can use them any way I want" is just plain silly. It's the same thing as saying, "I paid the rent last month, why do I have to pay this month?"
If you choose to bank those points forward to a future year, you are actually putting more points in that UY than there are room-nights. If you borrow from a future year, you are creating a situation where you are using points to gobble up accommodations which do not actually exist.
Now obviously, there is a lot of banking and borrowing back and forth, and it kinda-sorta balances out. But if DVC allowed you to reverse those decisions, it would upset the balance of the system and would create an unmanageable mess. So the transactions are non-reversible.
Most timeshare systems permit some flexibility of usage to overcome the fixed-week/use-it-or-lose-it model the industry started out with. Banking/borrowing is DVC's way.
Learn it; do it; deal with it.