How does Modern Money Theory deal with bank money?

Mike Segar/Reuters (original image modified)

Stephanie Kelton, a prominent Modern Money Theory (MMT) proponent, has a new book out, The Deficit Myth, and it is finally making the rounds of reviews by economists and commentators. As to be expected, there are some whataboutisms. In the case of Josh W. Mason’s largely positive review in the American Prospect, the question is: what about the banks?