A nice little restatement of some basic facts:
I often hear progressives say that Modern Monetary Theory (MMT) is all very well, but given the real politic, within which these debates are contested, it is better to rely on mainstream understandings to make the case for more government spending on progressive goals.
I remind these economists of the way that John Maynard Keynes used the (erroneous) neoclassical concept of marginal productivity theory for labour demand in The General Theory, to allow him to concentrate on the supply side, where he believed the differences between his approach and the orthodoxy could best be highlighted.
It was a decision that he regretted when it became obvious that the orthodoxy manipulated the debate to categorise Keynesβ quibbles as the special rather than the general case.
And the result was the neoclassical synthesis which dominated macroeconomics for the next several decades and allowed Monetarism an easier path and then the current New Keynesian paradigm to emerge.
The essential message of Keynes was quickly lost because he made that sort of strategic error β using neoclassical framing.