I'm as much an MMTer as the next guy, but printing money is inflationary unless it increases outputs. If we print money faster than we can produce things for it to buy, bad things happen. The problem is that we can't know how much excess capacity new money will put to work. So the measurable debt/GDP ratio becomes a proxy for the non-measurable negative output gap. Some of us know it's a proxy, and some of us don't, but, either way, it is still a flashing red light.