Their studies are wrong. MMT drives rate hikes

Even a temporary monetised fiscal stimulus could trigger expectations, especially from the government, that a one-time use could easily become permanent. In turn, a permanent recourse to monetary issuance would lead to a flight from currency and to hyperinflation.

MMT’s claim that government spending is only constrained by the “inflationary” ceiling, which binds when all productive resources are fully employed (Mitchell, 2020), is incomplete. MMT does not address the opportunity costs and distributional consequences of the monetisation of deficits by the central bank, e.g. its impact on asset prices, that may affect both the demand and the supply side of the economy and therefore the inflation constraint, even before full employment is reached.

MMT argues that the normal interest rate for government debt should be very low or even zero. This assumption begs the question of the plausibility of interest rates permanently below the growth rate of the economy.

A government deficit may lead to an increase in longer-term interest rates (Lavoie, 2019; Palley, 2019b) if financial markets expect high future inflation well before full employment has been reached. If the debt is not willingly absorbed by the market, the recourse by the government to financial repression would not prevent interest rates rising in private credit markets with adverse consequences in terms of monetary and financial stability.