The point is that progressives currently have it structured such that the income tax beneficiaries get to vote more taxes upon the income tax payers.
Go flat, include everyone, level the field, and they will not be so quick to increase a tax they know they’ll never have to pay.
As for completely eliminating income tax, if I thought there was a political possibility of doing that, short of a collapse of our current federal system of government and reversion to a loose confederacy of states, I’d be for it.
Give it up. We’ve restricted this to FEDERAL PERSONAL INCOME TAX. There are plenty of other tax methods out there.