If the upper beam is not straight, the lower ones will go aslant

Chinese Proverb

Modern Monetary Theory or Modern Money Theory (MMT) is a heterodox macroeconomic theory that describes currency as a public monopoly for a government and unemployment as the evidence that a currency monopolist is restricting the supply of the financial assets needed to pay taxes and satisfy savings desires.[1][2] MMT is seen as an evolution of chartalism and is sometimes referred to as neo-chartalism.

https://en.wikipedia.org/wiki/Modern_Monetary_Theory

When government sets out a measuring system, it is for the common understanding of a measurement in certain area.  If there is no “Monopolized” (as it describes) measuring system, people can claim whatever they want and little mutual agreement will happen.  There will be little transaction of anything between two parties. 

Money is the same.  The Government won’t have the monopolized value on currency.  They have some influence over the value of currency but they don’t have monopolized or absolute power over setting the value of currency. 

From the history of the mighty Rome or Yuan dynasty, doesn’t matter how powerful and how big a country was, they still don’t get to fully control the value of their currency in terms of printing money.  

War typically gives high “employment”.  In fact, during ww2, there was a period of time of full employment.  Rome were plagued by government debt and war which were the 2 main reasons for their demise.  Even without war, using government projects and debts to create “full employment” then to tax will not control inflation because inflating asset price and inflating cost of living are two different things.  One of the reason is tax will not be very effective to control money and money often run from tax (legally or illegally).