Gold has been exchangeable longer and in more places than the US dollar or British pound. I'm somewhat sure (with some periods of exception, like from when FDR froze the gold window until when Nixon busted it) that gold has been the better or nearly equivalent *store* of value, as dollars or pounds kept in the most reliably quickly-liquid stores.
Well private ownership of gold was illegal in 1970 for starters. Transactions in gold were never very accurate or efficient. Gold can be an ASSET and assets can increase in value. As an asset gold has lagged behind many other assets in appreciation.
Had you bought an ounce of gold in 1981 for almost $900. Today you could buy only $500 worth of stuff with it and that is after the doubling over the last five years.
For twenty five years it has been a horrible investment.