I don’t support the mortgage interest deduction and have said so many times. It is stupid policy. That being said, the means by which the Republicans are eliminating it is beyond dumb. Other countries that have eliminated it did so gradually over a number of years in order to prevent a sharp, immediate contraction in housing prices and a sudden and sharp increase in monthly housing costs that can lead to defaults on loans, undermine the value of securitized loans (like what caused the housing crisis!), etc.
As for state and local tax deductions I’m fine with eliminating them but in that case they need to be replaced by either significantly larger federal spending in those states or other deductions. The states that benefit from SALT are not being subsidized by you for their high taxes, they are in fact likely subsidizing your presumably low tax state. It is not a coincidence that these high tax, high service states are the most productive in the US and that every state or nearly every state significantly affected by this is a large net donor of federal revenues. Is there any good policy reason to make this disparity far more severe in order to cut taxes on the rich?
So out together you’re talking about tens or hundreds of billions of extra tax dollars being suddenly extracted from our most productive areas overnight. This is very bad economic policy.
Does that clear up why this is stupid?