Your thought experiment involves people working for free: being paid with money they can't actually use because they're isolated from the rest of the economy an

Your thought experiment involves people working for free: being paid with money they can't actually use because they're isolated from the rest of the economy and can't spend that money. Nobody would agree to this. In practice, the people receiving the printed money would not be isolated from the rest of the economy and would be purchasing goods and services with their subsidies and driving up the prices of those products. You're right that if spending printed money created gains in production to match the increase in money supply it wouldn't result in inflation. That's correct, but I seriously doubt that this is how MMT would work out in practice. Most MMT evangelists aren't trying to get a favorable return on investment. They're looking to fund massive social spending programs like UBI, government healthcare, or decarbonization of energy production. To be clear, some of these are important projects but we shouldn't kid ourselves into thinking that printing trillions of dollars to pay for them isn't going to affect inflation. They're worth paying for because of the benefits they bring and disasters they avert, not because they're going to produce a return on investment.