Quote from crash n burn:
FIAT currency system has allowed the world to grow at sustained rate for the course of last 50 years. with a commodity backed commodity, we would see prolonged depressions that would lead to generalized starvation and revolt.
in addition, since these commodities are extracted from the soil and are concentrated in specific regions of the globe, a global gold or oil backed currency would lead to a shift of power from the actual economic super powers to others. i dont see the USA, Europe and Japan throwing out their economic supremacy to Australia, South Africa, Russia or Brazil just for fun, really.