MMT is a brilliantly evil and fully workable theory of currency and taxation.
In fact, you can greatly improve the efficiency of MMT by permitting the government more power than merely the power to tax gains; if you permit government to confiscate your property and sell it as well as confiscate your currency in proportion to how valuable all your property is, economic control can be fine tuned and even combine with any other form of control one may want to implement.
That said, since most people are against theft, MMT is probably as far as they’ll try to push the theft. Obscuring theft by abusing the widespread ignorance regarding money is brilliantly evil and not that much different than stealing any amount from anyone at any time.