Yes this is all true, MMT is a theory. It's in the name. Yes, it's controversial.

But those points have nothing to do with the validity of the statements I made, including the ones you quote. It's a very broad economic theory covering how things should be done etc etc.

My point is not founded on MMT, I referred to it as a "look this stuff up by starting here". That's why it's only mentioned in the edit. The mere fact that this is an even remotely acceptable implies the statements I made is valid - otherwise MMT would fall apart at its seams.

Taxes funding things is indeed a myth, and they're essentially a money void. Go read up on those specifics if you want to get into it. The video I linked has a literal explanation of this like 30 seconds later. When congress approves programs, they just allocate new funds to it, and move on. There's no digging up taxes to point towards it.

You could begin making an argument it has implications for the validity and reliability of the sovereign currency, but it has no real relationship to taxes. That's just not how modern economics work anymore.