The existence of unsecured debt is a direct result of the fact that slavery is illegal. If slavery was legal there would be no such thing as unsecured debt because the person in debt could be taken and owned as collateral for the unpaid sum.
This is an interesting take.
Also, that "too big to fail" line (as far as I know) takes its roots in things that were espoused by the cotton industry back in the day. There were tons of people taking on debt to buy slaves, and most of them were producing cotton. The supply was crushing the demand. This was used as an excuse to prop up an abhorrently unethical industry.