It doesn't "usurp" anything at all and especially not the state and local tax systems. Those are (still) up to the state and local governments.
If you are going to go back several days and start spamming, at least try to figure out what the discussion was that was taking place before commencing to dispense your verbal vomit.
xzins wasn't talking about your idiotic scam. He was talking about his own idea for a single tax system to replace state and local systems.
Try to keep up.