Actually we are now in a fiat money system. The US came off the gold standard in 1971. This misconsception has hurt the US greatly as we don't understand how our monetary system actually functions. We still have many of the same laws amd accounting practices from when we were still on the gold standard. This hinders the US and the global economy even greatly. Most pointedly right now being the national debt debate.
I know I'm not answering you question really directly but you bring up and excellent point. In the US the only thing keeping the Dollar as the main currency to barter with and exchange good is that the federal government creates it and enforces its validity by demanding taxes be paid in the form of Dollars. The federal government MUST spend money ( their are various ways they do this) into the economy in order to tax it. The federal government is also the monopoly supplier of the Dollar, thus it never needs to tax or borrow to spend anything. They do have to account for inflation which is not just increased by money supply but moreso by the US economies productive capacity. Just as under the gold standard, if the government found more gold they could spend more and create more paper money, in fiat money, our current system. The government can create and spend money up to the US's productive capacity without any inflation and we are no where near there now. The US needs updated accounting laws to understand this and advance...