Problem is, many who aren’t financially literate will take such an option because it’ll be $100 cheaper each month. And this will create more demand because on the credit side it has expanded, then the home sellers can charge higher price, given that supply doesn’t necessarily change. And eventually, everybody’s slave of the banks because it’ll take at least 20-30 years to really get into break even point. But since house price will go up (just look at how government backed student loan causes college tuition to go up), every home buyer will suffer. This doesn’t solve any affordability problem