Nobody made that point (so far). The point was that your suggested link to an aging population is nonsense and that erasing debt destroys faith in the basic concept of debt. No investor will ever invest in debt again unless there are mechanisms in place that place powers in an investor's toolset to enforce the repayment of debt. Anyone who ever invests again a penny in Argentina should be crucified or deserves to lose every single last penny. That includes fund managers who manage pension accounts and bought Argentinian sovereign debt. Rewarding bad actors reinforces bad principles and destroys the faith that is necessary for debt to exist in the first place.
By forgive, I mean the Fed should just forgive the US Treasury. So no one other than the Fed is missign money owed.