The problem is that physical silver coin is not ever going to be used as currency ever again, no matter what happens. Period.
1. We are in a digital age and no one is going backwards, no matter what happens. Period.
2. When global collapses ensues such that you think you might be able to use metal coinage, what actually happens is as follows.
You can't transfer digital value when electricity and internet are down. You need substitutes. And I don't mean permanently disrupted, just a week is enough to remember the "barbaric" past. Sure, food will be a priority but those who have access to large stockpiles of food will accept barbaric metals and other such items of value. They would accept digital but electricity and internet will be turned on next week only and so they accept what they have confidence about, many people have confidence about metals. Not to mention that two-three billion people in the world don't have bank accounts (including developed countries) and aren't really accustomed to and haven't gone full digital, and I don't mean tribal people of some remote islands. Everyone knows metals, they will always have some value.
- As Fernando FerFAL Aguirre points out, only the currency that can be exchanged external to the crisis area has value. People are not bartering silver dimes, rather if you had German DMarks in Bosnia or USA dollars in Argentina, then these were accepted and liquid. Gold coins were much more difficult to liquidate because there is a funnel of few dealers that can't actually exchange them for the externally liquid currencies of USA dollars.
- As Dmitry Orlov points out, everyone's priority is on food, security, and transportation. Direct trade of these is more valued than some metal which can't be traded for these needs, because these metals are not liquid.
- Armstrong has also explained that gold and silver only have a value for as long as the collapse is not total and there is still an external market. During Dark Ages such as in Japan or fall of Rome, the gold and silver become entirely illiquid (is buried in the ground) and only food, guns, fuel, and alcohol+cigarettes become money.
- This is relevant if other fiat currencies have stable value. In FerFAL's time they did. This is not guaranteed as central banks are all in a competitive devaluation race.
- There is a lot of ground and time space leading to what you call total collapse and between that and now there could be temporary disruptions of infrastructure that call for trading metals for items of necessity, while access to digital is limited. A simplest case is ATM malfunction, bank is closed, you have a gold chain you can take to the pawn shop. Expand that to ATMs and banks being closed for a week.
You can't easily stockpile food to last you a year of these temporary disruptions, unless we talk canned food which is shit and can give you major stomach issues after you consume it for a couple of weeks. You see just two extreme ends: dark age and digital age, one or the other happening fast - this is your problem. There is a lot of distance and a lot of opportunities to use metals and crypto and other items of value, depending where and when you are. Even in most dire circumstances (war, widespread famine) there are always stockpiles of food somewhere that someone has access to and will sell for the right price in valuable items.