Is it cartel or common sense? If one lemming decides not to leap over the cliff, and the rest start to follow his lead, is that a cartel? If every airline provided the same basic level of service that WN does, then fares would drop to its level and the carriers might be able to make money. But as long as there are customers for premium service and more than bare bones services, cost structures at the other carriers will be higher, and they will have to charge more for their seats.

Also remember that WN does not interline, goes point to point with a limited route system and has no international service. If all the majors copied this model, how would Americans travel to the rest of the world? Use foreign carriers?

One cannot compare WN and the rest of the industry, so don't over simplify the situation by trying to do so.