Interest was paid on gold deposits prior to the 1933 confiscation, although rates under the gold standard were fairly low. So, the only real reason gold doesn’t pay interest is because the government forbade it! I’m no goldbug, but thems the facts.
None of it is the point. The point was merely that bonds denominated in a fiat currency do tend to hold their value over time, interest in, even if fiat money stuffed in a cookie jar does. The reason is obvious - men demand higher interest when inflation is higher, so real rates tend to at least zero in the logn run, and this economic fact is entirely independent of the monetary system. Markets and men's motivations, not laws, decide such things.
Government "forbade" interest on checking accounts too. It just differentiated one kind of account from another, it didn't prevent bank accounts that earn interest, or spending from interest bearing accounts. Clumsy regulations can change forms but they do not touch economic substance. Which, same as it ever was, is up to the contracting parties to set any way they please.