If you didn't nail the "why", you certainly came about as close as one can get. From my personal experience, I think that we may be missing the "social clubs"

If you didn't nail the "why", you certainly came about as close as one can get. From my personal experience, I think that we may be missing the "social clubs" from past decades. There's something to being a new person to a club or group that forces people to stop thinking of themselves as special/unique and defer to the group dynamic, and I think this is (in most cases) a healthy process. I've played ice hockey with the same group of guys/gals for ~15 years, and when a person joins our group, you can tell almost immediately if they're going to last: if they keep their mouth shut on the ice and let their playing do the talking, but off the ice they are sociable and have interesting things to add to the conversation, then they will be a long-term member. If they, instead, start whining about this or that on the ice or don't want to join in some of the off-ice socializing, they typically aren't going to last very long.