The operation "paying off debt" doesn't exist. This is because positive interest rates imply demand for debt outstripping savings. For debt to be paid off, the interest rate would have to reflect savings outstripping debt and forcing a reduction of savings as there cannot be monetary savings without debt, it would be just an empty piece of paper otherwise. In such a scenario, you would need a negative interest rate but since that isn't politically feasible. The only path you can take is through inflation and positive interest. This is what Keynes meant by gold digging, if private business and political interests prevent the obvious and rational solutions, then even the dumbest solution will be better than nothing. So, rather than implement a mechanic that allows a nominal reduction in debt, we need a central bank that constantly keeps inflation high enough to not let ourselves drown in debt, which is why the target is 2% and not 0%.