Earlier quoted context omitted.
In this age of more or less fully network connected devices, this kind of a setup seems archaic in the extreme, probably likely to be some hangover from the 70s or 80s.
Apparently Southwest is one of the biggest offenders in the airline industry when it comes to not investing in their IT infrastructure. You can only get away with that sort of debt for so long.
Kevlin Henney has recently suggested we should stop calling it technical debt, and start calling it technical neglect instead.
Managed debt is a useful thing, if you ignore debt, you end up out of business.