> MMT forgets that people won’t lend to the govt if the government is going around telling everyone the way they intend on paying the borrowers back is by making the currency they borrowed in worthless. ... The moment the government makes MMT official policy no one is gonna lend to that government.
Your premise about the currency becoming worthless is not self-evident. MMT's explicit predicate suggests the currency won't become worthless: MMT assumes there is enough slack productive capacity in the economy — or that additional capacity will be added — to accommodate the increase in demand from the additional money in the system. When that's the case, prices shouldn't rise unacceptably.
MMT makes intuitive sense, but right now we're all just speculating how the populace (and the bond market) would react to it. We also don't know whether the government has enough "instrumentation and control" to be able to manage it effectively.
MMT can only work in a world where the government is explicitly not doing MMT. The moment the government makes MMT official policy no one is gonna lend to that government.