Banks and businesses have been doing this for years. They weigh the economic impact of supporting an unprofitable entity versus the impact of letting it go. I don't see why people insist that other people are "morally" obliged to continue to pay a mortgage.

A mortgage is a business contract. The banks evaluate you in terms of risk of not paying and you evaluate the prospects of the mortgage contract they write for you. There's no blood oath or secret brotherhood you join.