Additionally, you can't say the bank has put nothing into the deal. Clearly, the fiat money offered by the bank to the home buyer was worth the consideration of allowing the bank to hold a lien on the house. Otherwise, what incentive was there for the homeowner to buy the home?
If you're talking about the mortgage securities crisis in 2008, it is a mistake to reduce it to "banks were hustling people.". If you're referring to something else, I'm curious what that situation was so I can research it.
RE: Two Formulas Banks Use to See If You Qualify for a Loan