Its intresting and makes some sense to me. Its been a few years but if i remeber the premises of the book correctly you could TL;DR the book as "money and credit was made to keep track of debt"

So I guess I'm between the two schools of thought. If money and credit was made to keep track of, and settle debts then I think the idea of "money being an emergent property of the most saleable good that keeps value over time" was a quest for efficiency of debt settlement.

The use of gold or whatever was used as money in whatever era was just the most effective thing to settle debts at the time. The medium has always changed. But harder moneys seem to last the longest.