It seems like it's pure hell when accounts receivable don't circulate between companies...

It's nothing new, but
If Company A provides raw materials, Company B manufactures, and Company C is the final recipient,
at least with government or public entities, you can expect payment within a reasonable timeframe.
But with private sector clients, you never know when you'll actually collect the money.
Company B needs to receive payment to pay for the materials, but then they have to deal with collection calls or sales reps visiting Company A to discuss it.
As this drags on, the supplier eventually says they'll only pay once they receive their own funds (which is natural for Company A, regardless of B's situation), but then B needs raw materials to continue manufacturing... On top of that, they have to pay for equipment services and employee salaries.
Mail carriers are constantly delivering court documents; even a single company can have multiple ongoing legal cases due to unpaid receivables.