ב''ה,
Sure is great every country outside USA has separate internal and trade currencies yet anyone pretends this matters.
The IMF prohibits countries from manipulating their currencies. Specifically, Article IV requires member countries to "avoid manipulating exchange rates" to prevent "effective balance of payments adjustment" or to gain an "unfair competitive advantage."
It's an unfair advantage in trade.
But the US Dollar's dominance is actually, despite the skeptics, basically at an all time high.
Most countries outside the U.S. effectively operate with one currency but treat its role differently for internal stability versus external competitiveness. Domestically China uses the onshore yuan (CNY), which is tightly controlled within its borders. But Internationally China uses the offshore yuan (CNH), which trades more freely in global markets, providing a degree of separation between internal and external currency behavior.
This animated graphic shows the U.S. dollar, the world's primary reserve currency, as a share of foreign reserves since 1900.
www.visualcapitalist.com
This chart shows the currency composition of payments processed on SWIFT.
www.statista.com