FWIW, I found your points interesting, and I agree that all mortgages are about the ability to repay. Wasn't that at the root of the 2008 subprime mortgage crisis?

And ability to repay, in my understanding= Capital, Capacity, Credit history, Collateral

-Capital: Down payment, loan fees, closing costs, escrow impounds, reserves, moving expenses

-Capacity: Current income, income history & future earning potential, Amount owed on installment accounts & revolving charge accounts

-Credit history: Current liabilities and past history

-Collateral: i.e., Is the house worth what you are paying for it, and if not, that has to be fixed before closing.

I learned the above through a home-buyer's education class I'm taking in order to qualify for a down-payment assistance program (https://housingtrustsv.org/programs/empowerhomebuyersscc/).