MMT by itself is missing something vital; a source of wealth.
You might remember the Bitcoin as a Kardashev Hinge story Nuno, in there explains a perfectly fine source, which solves all the problems; the energy of the sun.
At last we are connecting with it, and Bitcoin is the key.
Of course as money comes to align with sunlight, it has to appear initially to run away from how we previously saw it align with gold.
In this new scenario, we will become more interested in the derivative of the movement of money, rather than the absolute value.
In other words, the rate and volume of flow.
As long as the total rate of issue of all currencies does not exceed the total value of solar power currently being utilised by humanity, the value of any particular freely issued currency, relative to all others, will be sustained.
To guarantee that, the issuers of each currency must hold a certain share of Bitcoin.
Remember, each Bitcoin is ultimately worth about 1MW of solar energy capacity.

I find it most useful and satisfying to think of this as the “first shoots” phase of our transition towards becoming like plants in nature, as a species.

Plants embrace the energy of the sun as the sole source of energy on behalf of all life on Earth.

Now we also will do the same, on behalf of all humanity.