Housing industry lobbyists often make the case that, whatever you think of the mortgage interest deduction, now would be a terrible time to eliminate or restructure the subsidy.
However, it was massive government support for the housing industry through the mortgage deduction, rules such as the Community Reinvestment Act, and a multitude of subsidy programs that created the property bubble which burst so disastrously in 2008.
In 1960 only 15% of federal income tax returns had a zero tax liability, due mostly to low taxable income, a standard deduction, the personal exemption, the dependent exemption, and the Earned Income Tax Credit (a direct subsidy to people for being poor).