Southwest added a much higher cash required fee than the other airlines for the same itinerary.
And the rest of your answer is bullshit as well. It has nothing to do with connecting through any hub since United also offers much more direct flights to the same destination for cash, but try and get there using frequent flyer miles and they'll create an itinerary that has you flying to lateral points on the map that have nothing to do with reaching your final destination. It is nothing more than creating a trip that is so unappealing that you will just bend over and pay cash so you aren't spending half your vacation waiting in airports.