You have to back up and figure out what the hell you are dealing with first. The first issue is that a digital currency where transactions are not blinded and transaction validators are designed to centralize is LITERALLY a 1984 slave system. The same system described by Aaron Russo where you're required to worship the communist govt and do everything they say, and if you don't, they simply refuse to process any of your transactions and your money is essentially turned off/ceases to exist/confiscated.
Using or building anything on top of such a system is pure idiocy. This is why people say the existence of physical money is a basic human right in comparison to a "cashless society". Through the attempt to try and minimize hops and channels constantly open, the Lightning Network will obviously evolve into the typical hub and spoke model like all critics suggest. Instead of having transaction validators (aka miners) in the normal bitcoin model that can go under, fail, or be replaced, this converts bitcoin into the traditional "too big to fail" banking model where those hub and spokes will be run by people like Goldman Sachs and never be replaced.
As you can see, the evolution of bitcoin is complete dogshit no matter if you use the base protocol or LN. This is why anyone who supports digital "money" over silver and gold is a complete idiot and the enemy of humanity. Nothing about this stuff is "money", it's all just a permissioned ledger control grid.
With physical money involving gold silver copper there was still a problem with failure to maintain a standard measure. So gold coins or whatever end up having to be a set dimension and a known weight so it can be measured and shown to be true value.
In the old days, whether it's the Romans or early Americans, the common man had little or no ability to test the purity and weights of metal coins they were using. They mostly had to rely on the stamp of the king or govt declaring what it was they're holding. In other words, they weren't even using metals as money at all in most cases, but instead were using fiat in practice. In the case of the 21st century, you can simply ping a coin while holding it next to the microphone of a phone, and the android app will tell you if the sound wave corresponds to a real .999 silver American eagle or not.
So, in effect, metals are MORE sound as money in the 21st century than when used in the past because they can easily be verified by everyone now and no longer function as fiat. Instead of being a "barbarous relic", they actually become MORE useful because verifying them is easier. For verifying huge 1000 oz govt bars and such, they use things like X-ray machines, but for coins, things like sound wave tests work fine and anyone can do it.