Currencies are arbitrary. Gold has some industrial value, but essentially no utility to own.
Imagine the global economy collapses, and you have 100 tons of gold - what good will it do you?
Currencies have value based on what you can exchange them for - that is why dollars (and euros and all fiat) are valuable. People will give me things I want if I give them some paper. Gold as a currency is the same, but only as long as people value it. Exactly the same as fiat. It being limited only affects the per-unit PRICE assuming some value, it doesn't give it value to begin with.