>>520335688
not only has that decision deemed good enough for thousands of years, it's also based on availability.
For historic people, fish was infinite and came from the sea. Cow Milk, for what it's worth, also seemingly infinite. How do you derive value? Is fishing harder than raising cattle?
Along came the miners who found some shiny rocks. They were really beautiful, but whereever they looked, no shot at finding more. Nowadays you can tech it, but turns out that's a shitload of work as well, and they don't come packed in neat clumps either, you have to mulch a goddamn mountain to get some.
Rare earths could go into the same category - available everywhere, but in minute quantities.
Purifying Gold is a shitton of labour, and in stark contrast to fish and milk - you won't eat that. Perfect as money, it never spoils. Silver gets milk spots, Gold? Nope. Both are relatively rare, and well known to be 1:8 in the earth's crust.