IMO the SALT deduction is a horrible thing and allows state governments to become way too bloated.

Under a federalist, state-first system, the federal government shouldn’t consider mandated transfers to state (including administrative subdivisions) government which plays the primary role in the conditions of local commerce which enables income as part of the free income of a taxpayer subject to taxation (this also avoids federal taxes altering the calculus of net benefit in state democratic decisionmaking on tax and spending.) In a federal-first, centralized system, ignoring state taxes consistently makes sense. In either case, a limited SALT deduction has no principled justification, and is simply an effort to use the power of federal tax policy to put a federal thumb on the scales of state decisionmaking to get the successful states whose economic success makes them net contributors to the federal government to adopt tax and spending policies more like those characterizing the politically-overrepresented but less successful states that are net drains on federal resources, leveling the playing field by making every place suck equally, so at least the former can’t make the latter look so bad any more, while advancing the Norquistian vision of shrinking the size of government to where it can be drowned in a bathtub, without concern for thr consequences, because ideology.