A really good essay, the writer knows his stuff, the points are soundly argued and I agree with all, except one.
- that enormous government borrowing must lead to sudden crisis and national financial collapse. (my words)
I do not actually disagree, but I question that proposition.

It is natural to expect that, it always happens to individuals and corporates. But perhaps it matters who owns the debt. If the debt owners have a crucial stake in the national economy such as big banks, cronies, other nations who need to sell to the big consumer to keep their own economy going, or, suppose the debt owner is the same entity as the debtor? Or, if not legally the same, one has complete control over the other. [ Does not the US government have full control over the Fed Reserve even tho' there is no ownership, or is it the other way round? ]
In such cases, especially the last, what exactly is the risk?
This kind and magnitude of debt creation is done with no intention of it ever being repaid, interest rates may be reset, they could be set negative. The money used to make the loan is created not from more or better products or services but by the usual (and unfortunate) mechanisms usually called printing. The effect of the debt is to enable the electorate to vote itself more benefits, this they will get, at least in money terms, government gets to reward banking cronies with commissions and gets increasing influence and control of the economy gaining a steadily increasing proportion of the national wealth to dispose and allocate. I do not argue that this is in any way fair, responsible, efficient, but it could go on for much longer than if borrowing were from independent entities. There will of course be declines in productivity and in production, as stated in the essay, but I suggest that this can go on for decades.