I don't think it's weird per se. I hate to paint with a very large brush but think about the demographics. There aren't any poor kids going to Mystic or Waldemar or any of the other summer camps that have waiting lists, interviews and acceptance ceremonies (Mystic has all of those, I believe). FF to when these kids have kids of their own. Their daughters MUST go to Mystic, which is still revered by these mothers who are in their 20's, 30's or 40's. You probably have a better chance if you're somewhat active in the camp's recruitment activities, etc, just like in many other organizations. Sounds like there's room for 750 or so campers per session. Anyway, many of these women do not work (again, broad brush) as they're full-time raising children (with or without help). This is something for them to do to stay active or engaged with other similar demographic peers and so on.
I don't think any of that is particularly weird. As mentioned earlier, my best friend from HS (may he RIP) met his future wife while working in the camp kitchen several summers. She was a former camper and was at time the equestrian instructor. They had four girls and every year, even before the girls were even old enough to attend would go up to Mystic and visit. I think they even stayed there some of the time when camp wasn't in session. The couple who own the camp and perished on Friday morning were revered by just about anyone who ever had reason to cross paths with Camp Mystic.