The issue here is divorcing budgeting from democracy, which I believe Germany did after their travails?

Similar to how well-run companies separate their CFO duties (how much we can and can't afford) and from their CEO ones (what we choose to invest that in).

The US has that in the monetary side (for now, the Fed) but has never had that on the budgetary side with Congress being concerned with being reelected (and bringing home the bacon being a reliable way to make that happen).

Paying down US debt seriously will only happen if Congress and the President choose to cede part of their spending cap authority to an independent entity, and that's never likely to happen.

It's really hard to do that in the general case. As the aphorism goes, "Show me your budgets and I'll show you your priorities", and in a democratic society, the priorities are supposed to be decided by the voters.

You could however envision a system where the bottom-line (the overall budget surplus or deficit) is dictated algorithmically by economic conditions, with the government free to move funds between different priorities, raise taxes, or cut overall spending as long as they met the target budget surplus. Actually wouldn't be a bad idea; it mimics how private organizations and households have to adjust their spending to fit constraints. The whole idea of algorithmic central banking and algorithmic fiscal policy could be quite interesting, particularly now that you have cryptocurrency where you can build algorithms into the nature of money itself.