While I do agree with this article's identification of the primary utility of crytpocurrencies, we should consider the optimizations that it can provide through a more effective use of resources. I'll go ahead and TL;DR here before the succeeding wall of text:

Crypto currency will result in a net gain of useful resources by using pulses of electrical current. Silver and gold are more useful for their elemental properties rather than their primitive use as trading mediums.

The Physical and Socioeconomic Properties of Elements and Compounds

Gold, silver, platinum, and diamond. For the past ~6000 years, these three elements and one carbon structure have been sought after mostly as mediums of trade. “Various forms of livestock, in particular cattle, and grains were the earliest forms used to settle trades and payment for good goods and services. Cattle are hard to carry in your pocket and grains spoil so an alternative currency was needed”. The value of these elements during the early economic development is attributed to their scarcity, resistance to corrosion/oxidization, tensile strength (except Au/Ag, which are very malleable), structural integrity under extreme conditions (a diamond is forever, just like the love between two people). These can thus be relied upon to transfer value between two parties.

Advancements of the past 100 years have suggested new uses for these materials. Certainly diamond will continue to be sought after for its utility in drilling and abrasives, but the electrification of civilization has suggested new uses for these materials. Silver has the highest electrical conductivity of any element, but tarnishes easily when exposed to oxygen. It replaced copper as a conductor during early 20th century war-time resource rationing. Platinum has an extraordinary resistance to corrosion, and can be used to coat electrodes to split water for hydrogen and oxygen extraction (though extracting hydrogen from methane is more economical, but carbon monoxide is a byproduct).

These materials are too expensive to replace copper, but why are they expensive? Thousands of years of economics.

Silver dining utensils aren’t valued for their superior electrical conductivity. A host/hostess sets out the “good silverware” for special occasions when it would be advantageous to advertise wealth to others, or because it comforting to hold value while eating a meal.

“Solid state electronic devices use very low voltages and currents which are easily interrupted by corrosion or tarnish at the contact points.” The gold stored in sovereign vaults guarded by pensioned government employees 24/7 is not secured under these conditions because of its capacity to increase the durability of electrical contacts. It is valuable because of it, but expensive only because we are delaying the retirement of traditional mediums of resource exchange.

The abrupt arrival of the digital age has produced technologies that continue to eliminate the middlemen and inefficiencies that are parasitic to the process of transferring value. Web payment services do much to reduce physical transportation of metal and paper currencies, which saves energy and time and therefore creates more value because it directly contests systems that were already in place (though the modern currency thief is going to exploit network vulnerabilities, in the same way train robbers would exploit vast, unsecured distances between towns during the westward expansion of early America). The blockchain is an even newer technology that is continuing to be refined, and is expected to be immune to counterfeit and centralized control. Bitcoin and Ethereum are the most widely used cryptocurrencies that use the blockchain, and their value remains constant across all currencies. These concepts (especially Ethereum) are the digital manifestations of the theory of democracy - unhindered by loopholes, corruption, indecision, and private-interests.

A re-evaluation of value transfer mediums is necessary because of things like supercapacitor technology. Energy storage is the primary bottleneck in the implementation of energy harvesting mechanisms, as the sun only gives usable energy to a region for ~8 hours a day, and the rate at which the wind blows is inconsistent, albeit predictable. Silver is a useful material, not because of its electrical conductivity (which is on par with copper), but because its unmatched ionic conductivity. The Lithium-ion battery functions because of the exchange of ions between two conductive materials, and the energy density of a cell relies on the composition of the anode, cathode, and electrolyte. The primary determinant of this composition is the balance of value versus performance. Prohibitive value only exists when there is competition for the uses of a resource. Reduce this competition, and gain new utility.