This simplification misses the point. Unlike paper money and stocks you can't print more Gold. That's why people fall back to it again and again. Also it has _some_ intrinsic value in various applications. I am not arguing we should be using Gold, only that the statement you make, while true on the surface, glosses over the entirety of the interesting and relevant points about its use as money, historically and today.
Gold is a noble metal and does not corrode. That is its main value as currency. It conveys a feeling of durability.
Gold has a couple other things going for it. It's difficult to counterfeit, anything denser than it is more expensive(and usually radioactive). Tungsten is close enough to be a viable alternative, but is very difficult to work with, so this is only a modern (1980s on) problem. Additionally it is "appropriately" rare. Try using sand as a currency, you'll need a fleet of dump trucks. You can transport a significant amount of gold on your person, but if you tried that with Californium you would probably lose the dust sized particle that represents your life's savings.