In my limited understanding - in MMT because the US is the currency of choice then it can make up as much money as it wants. My thought on this is though - if the US dollar becomes, basically, gibberish because it's been pumped so high (e.g. the US Debt keeps going up and up), then it will be abandoned and some other currency will become the standard, at this point the US is in big trouble. Maybe someone more knowledgable in this stuff can point out the flaw? one of those things I've wondered for a while.
I think we are headed this way weather people want to or not.
Also, I think the rest of the world is headed this way under US based MMT weather they like it or not. Meaning the USA spends at will in their countries as well as its own states and just backs off once they have inflation.