“Apparently the logistics of getting pilots and flight crews to planes was a problem that day.”
That was part one of the problem.
They made it many times worse by failing to cancel flights immediately once they realized the shortfall so that folks did not have to waste their time going to the airport.
Having a problem is bad.
Being unable to realize you have a problem is very bad.
Being unable to act in response to a problem is very very bad.
Southwest also flies arcs instead of the more traditional hub look. That means that there aren’t a lot of turns. Take delta for example. They are based in Atlanta with hubs in map, Detroit and New York. Flights tend to fly from hub to destination and back.
Southwest on the other hand will fly a day that starts in the east and ends in the west. So when the system gets hammered they don’t have planes just laying around and crews as they are all scattered. Once everything got out of position with pilots that are hitting their mandatory rest time they were totally screwed.