Why did removing the silver content of coins not affect their fungibility?

[zimmah]

Silver value is not added to the fiat value, but it can replace it. (As long as it's not illegal to smelt them, which is often the case).

Of course you can always illegally smelt them.

Anyway when the silver content is less than the value of the coin it would not make sense to smelt them as you would lose value. Therefore in such a case would the value be the same.

In case the silver content is more than the coin itself than officially the coins are worth the same but in practice one could melt the silver coin and sell the silver for more money. (And repeat if he could buy more silver coins for sell than their true value).

[iopq]

Why not melt all those silver coins? Who is going to know once they are in the form of a bar?

Just start a Mexican melting operation.