I'm curious if there is a similar divide between individual sports and team sports. Virtually all the endurance sports discussed in this article are individual sports (with the possible exception of obstacle course races, but even then you aren't actively, directly engaged against another team like you are in sports like basketball, soccer, football, baseball, etc.)
My hypothesis is that getting an actual team (or teams) together to practice is something that is easier for people who are longer on time, shorter on money, while individual sports can be indulged by people with more money but where it is more difficult to synchronize schedules for team practice.