Provide easy credit to folks who eventually can't take on the payments (and the high interest rates). The realtors make a killing, while the creditors call for a bailout or "loan guarantees."
Judging from what I have seen happen to folks who get HUD loans, this would only make a bad problem worse.
So now we have big crooks who run a scam system who want to acctract little crooks who will scam the scam system because the big crooks will profit when the little crooks scam (try saying that fast). Meanwhile, if you are honest and pay your bills you will be treated like filth -- they will make it hard for you to get a loan and you will be taxed to subsidize the big crooks.