If the state money printing was at a reasonable level, and invested into public infrastructure, and education then in theory money printing wouldn't be a problem.
Unfortunately, in practice excess money is printed to fund wars, and social programs which causes potentially dangerous levels of inflation.
That's the main caveat / tradeoff that MMT advocates don't usually address.
The Debt has to be below 80% of GDP, interest rates have to be about 1% to 2% , & there has to be at least a small surplus or deficit.
Breaking these general rules causes issues, and could cause inflation to spiral out of control.