The spice must flow, property valuations must go up or the whole thing collapses. It's why non-SF-esque cities only allow expansion in-line with population growth or a little less because they will immediately be tarred and feathered if they make everyone's mortgage underwater.
To be clear this isn't a good thing, but no one wants to blink first and start another 2008.
You've securitized the cashflow from the property, so if that cashflow dips, the lender has an assurance they can reprice the security in line with your new cashflow story.
Even if you cover the shortfall in cashflow out of pocket, this is better for both you and the bank because you don't have to admit that the market rates at which you got your loan have changed.
Yeah. I can see how that would create perverse incentives downstream.