You're thinking like a capitalist. Stop that. Use your neurons.
Whatever the fuck dollars are, if you borrow an oz of gold from me and you're planning to pay me back in silver while the gold to silver ratio is 86 to 1, you'd be an idiot, but I can see how that would make me have some sympathy and leave interest out of it, so when you give me back 86 oz of silver, we'd be all set.
Whatever the fuck a government is, if it borrows gold according to some gold-dollar ratio and then these things can just be printed to pay you back, you'd have to be an idiot to leave interest out of it because that ratio is going to get worse for you when they print the things to pay you back.