Southwest's meltdown was about computer systems that coordinate "offline" based on assumptions instead of online based on passing information back and forth on a regular basis.
Southwest was a very reliable airline, it didn't have some sort of day-to-day understaffing problem, they executed an unorthodox business strategy [0] in the last year or so that has degraded their performance, and bad weather exacerbated the problem.
0: https://www.inc.com/kelly-main/southwest-becomes-one-of-amer...