[NeoTar]

> It would only make sense if it was given to be used a store of value, but they had perfectly good coins to pay salaries with.

The Roman Empire towards its end in the west had suffered from a lot of inflation, so coinage was either too expensive for everyday use (i.e. gold-coins, each of which would be a year's salary for a soldier), or worthless (basically just lumps of base-metal).

I think at a certain point taxes were required to be paid in goods rather than coin which really does show that your currency is worthless (when even the state refuses to accept it!)