Your statement is based on assumptions that just don't hold for many people. First and foremost, you imply a subjective utility of receiving a loan. For many people, having loans - especially collateralized against your home - has negative utility, not positive. Case in point: someone who'd need to take our a loan to pay the property tax.

But even if you were right for the majority of home owners: feel free to tax collateralized homes as commercial property based on the volume of the mortgage. Case solved.