When you buy a piece of real estate, certain instruments are held in trust until the note is satisfied. That trust enjoins both parties to perform according to the contract documents - but the bank didn’t. It’s a very hig probability the borrower will never own the home because the title is screwed up.
If I default, THEY get the house. That’s fair.
If they default, I get the house. That’s fair. Trouble is, I’ll never really own it without possible encumberances. The true holder of the original note just might show up some day. If I’ve paid the bank, should I also have to pay the legal holder of the note?
Come on - the answer to that is clear.
It’s stealing. Shame on you.