Oh please, the rebates insure everyone does not pay the same rate from the get go. Charge everyone the same amount! The only true solution to "Divide and Conquer".
It is the effective rate you have some control over - by saving and investing you can reduce your effective rate. You don't have that choice under the income tax.
The rebate, if it survives, would indeed affect the effective rate.
However, the point the tag lines makes is that marginal rates differ under the income tax - not so under the nrst.
This unified marginal rate has the effect of uniting ALL taxpayers against increases and in support of decreases.
Merry Christmas!