This was called Bancor and was proposed by John Maynard Keynes at Breton Woods. It was the major idea competing against the US pushing the dollar as the core of the monetary system and the US had all of the power at the time so that's why we're stuck with the USD now. It's actually a pretty interesting story and Planet Money covered it.

https://wikipedia.org/wiki/Bancor

https://www.npr.org/transcripts/526051566