Keep adding obligations to landlords to the point no one wants to be one. Then, if you can't, for any reason, secure a mortgage your only alternative is homeless. Sounds like a good idea.
Real estate, by multiple measures, is the most profitable industry in the US private sector. It is heavily taxed and regulated because it is a money-printing machine. We are not in danger of there being no landlords.
[1] https://ftalphaville.ft.com/2016/03/29/2157698/ranking-ameri...