But you actually prove the point of the article author by what you say. The fiat has this value because somebody simply decided it. There is no inherent value or use for the notes otherwise. They would not even worth the cost of the paper to print them. With unlimited renewable energy, in a few years, we could even transmute a "worthless" element to gold. Gold would have lost any value by scarcity. Bitcoin, on the other hand, once recognised by some governments, it is as good as fiat.
The whole point of the intrinsic value of a currency is that it is stupid, unless it is something that has practical use or value. Under this aspect, perhaps the last real currency with intrinsic value has probably been "salt" in the Middle Ages. Super expensive and used for a real reason: to make a miserable meal a little bit more palatable. ;)