Nice job.

I have one objection, one nit that the author does not pick. There is a difference between an economy running at full capacity and an economy with full employment. We can run out of cement before we run out of road-builders.

I do believe it is a good idea for monetary and fiscal policy to generate activity constrained by resources. But MMT does not say which resources will become the constraint, something that will vary with the projects the government chooses to fund or enable. If we could all be fully productive making yachts, we would not make yachts, because not everyone wants or can afford a yacht. The choice of outputs, and the choice of ways of choosing outputs are political, and MMT offers us no guidance in setting priorities.

An important thing to consider is why MMT matters. Think of MMT as analogous to relativity or quantum mechanics. We can allow that those theories are true but still not use them in our day-to-day applications of physical laws. My car runs just fine on Newton's laws. Only very fast or very small phenomena demand relativity and quantum theory. What is the analogy in economics to very fast or very small phenomena? I submit it is the shift toward very low marginal cost production. Modern technology has created a large and growing negative output gap, and only MMT can justify printing enough money to create enough demand to fill that gap. Because that gap needs to be filled, a justification for doing so must be found, and MMT is that justification. https://remarklj.medium.com/why-mmt-matters-now-949f0c9ad84a