> The money supply has almost quadrupled in the last 10 years, yet inflation has been low.
Explained by "traditional" (e.g., Keynesian) economics already:
* https://en.wikipedia.org/wiki/Zero_lower_bound
When QE was introduced, the US political Right went ape shit talking about inflation. Krugman (for one) predicted it would be fine because of interest rates, citing Japan as an example:
> Everyone knows about the infamous open letter warning Ben Bernanke not to engage in quantitative easing, lest he cause inflation and currency debasement; many are also familiar with the remarkable unwillingness of that letter’s signatories to admit, after more than four years of low inflation and a rising dollar, that they were wrong.
* https://krugman.blogs.nytimes.com/2015/02/12/qe-truthers/
If the private sector is not spending, then the public sector (gov't) should to take up the slack in a lack of demand:
> The problem, of course, is that you can’t cut interest rates below zero (if you try, lenders will just hoard cash.) So the Fed simply can’t do what the rule says it should.
>
> This is why we need a huge fiscal stimulus, unconventional monetary policy, and anything else you can think of to fight this slump. Quite literally, the usual rules no longer apply.
* https://krugman.blogs.nytimes.com/2009/01/17/zero-lower-boun...
There are a finite amount of resources in an economy, and when an "infinite" amount of cash goes after that, you start to big up prices: inflation. I don't think that mainstream (Left-leaning) are against deficit spending to boost the economy; it's just that many of them don't see MMT is adding to what they've already been saying.