Oil is mostly traded for dollars because everyone is selling/buying in dollars, so the best most liquid prices are in dollars, not because the US government for

Oil is mostly traded for dollars because everyone is selling/buying in dollars, so the best most liquid prices are in dollars, not because the US government forces it. You can sell oil in whatever currency you like - Iran settled in Euros before (and probably after) sanctions, there's physically settled oil futures denominated in Chinese Yuan and oil producing countries often make deals directly with other countries in currencies that offer less fluctuation.