There is some truth in this criticism of standard theories of the value of money. There are indeed two equilibria: the normal one, where paper money has value, and a weird one, where it is worthless. But Ludwig von Mises, for example, addressed this problem in 1912 with his Regression Theory of Money. Historically, money needed to be commodity money, or have commodity backing, in order to get started. But once it does get started, as a social institution, the demand for a medium of exchange supplements the industrial demand for the commodity, and the commodity backing can eventually be withdrawn as custom keeps us out of the weird equilibrium. (When Cambodia reintroduced paper money, after the fall of the Kymer Rouge, it could not create paper money ex nihilo, but initially made it convertible into rice, IIRC.)
Some interesting commentary as well.