You would think a libertarian would acknowledge that shielding YOUR money from taxation is a good thing, but you would be wrong. There are at least seven tax loss expenditures more costly to the tax man than the mortgage interest deduction, but their crazy war on it continues nonetheless. What it masks is the underlying hatred of conservatism homeownership represents. Homeowners settle down and raise kids instead of sacrificing themselves to the needs of global capitalists. That's their real problem with it.