- store of value
- unit of account (a measuring stick for value)
- medium of exchange
Allowing the financial system to inflate the money supply destroys two of those fundamental qualities. The fact it can additionally charge interest on the money funnels the stolen value into its hands.
Interest on money loaned out is the only incentive required for putting money to "productive uses". Nothing about hard money affects that. In fact inflation only causes the people at the top of the pyramid to hoard all of the economic value instead. They are buying up and hoarding the entire world with the wealth they are taking from the people.