the second half of the first sentence (and indeed the next sentence) claim mainstream economists think that only monetary policy matters.
This article has “straw man” written all over it. Reasons are thus.
Ralph Musgrave
2
In fairness, here is a direct quotation from SWL’s blog: “What about a world where monetary policy did successfully control demand and inflation, which is the world I’m writing about?”
https://mainlymacro.blogspot.co.uk/2016/03/mmt-and-mainstream-macro.html