Modern currency isn't backed by gold or any other precious material. We use fiat money. But I'm supposed to believe that the Ferengi run an interstellar government and are a major power in the galactic economy because they use bits of liquidy metal that they supposedly can't replicate as a currency? This situation is considered credible?
Why does something have to incapable of being replicated to be valuable? Paper, ink, and electrons are all ridiculously common, yet that's what we use in our current financial system. Why would a supposedly more advanced civilization use simple shiny rocks as a currency?