Any kind of standardization beyond that which is organic is synonymous with the word fiat. But people have been making unilateral decisions for a longer time than there have been enough things to standardize in the first place.

Also, I believe debasement of the monetary supply for the gain of the few at the expense of the many is actually a very old phenomenon, probably existing even before "money" was standardized in the first place. All it takes is to barter something which is counterfeit.

But at its core, I think the root cause of fiat is dishonesty. That's your real culprit, and it's a useful one because we can fix the dishonesty in ourselves.