The gov't can't issue 'too much' debt, unless it just burns the money it raises. Because it usually issues just enough to satisfy the domestic private sector's and foreign sector's propensity to net save.
When economy deteriorates, the private sector's propensity to save increases, as does the budget deficit. Budget deficit actually adds to private sector's net financial assets.
War is an example of destruction of wealth. They are literally burning those dollars. Now don't get me wrong here, of course those dollars are soldiers wages etc., but most of those thousands of soldiers could be doing something of actual VALUE, like running a business that produces more wealth. Nevermind the bombs, tanks, ships, etc. that are depleting the worlds net wealth by destroying and polluting.
How does budget deficit add to private net financial assets? Are you just talking strictly on paper or what? They're borrowing money from the FED who just creates it from nothing. That's currency debasement, that's inflation, which is just another tax on private sectors savings! They're stealing purchasing power from anyone who saves, which is definitely not adding to net financial assets!
You're talking about funds allocation, but it doesn't change the nature of budget deficits - sectoral imbalances.
No matter how government spends the money - it adds to the financial assets of domestic private or foreign sectors. It's called double-entry accounting principle.
And Treasury doesn't borrow from Fed, because it doesn't make much sense. Fed can't change sectoral balances by buying treasuries, it can only change the assets composition.
Well what I mean is analogous to the following:
If the private sector produces assorted crops for example, consumes some, then saves the rest. The excess production is wealth. I'm going to assume that you agree that the market is very efficient in general. If we introduce a government who says, "we'll handle the basic needs like roads, military, health, etc." and that government takes a large percentage of our production and inefficiently allocates to certain things, then we might as well be burning those crops, or as I put it, "flushing them down the toilet".
Well, you can't compare modern monetary system to primitive barter systems. It's not much more complicated, it's just different.
Fiat money is not a limited or scarce resource, it doesn't need to be grown or extracted. It's just numbers in the database. They can be created or destroyed instantly.
And when the Treasury spends, these "numbers" just migrate from its account at Fed to some account in the private sector (a simplified explanation). It can't be just "flushed down the toilet".