Communities are built round common interests. They die out when those common interests become stale. Obviously the people themselves don't have to die.
It's also not the case that they become anti-social but they limit the social groups to ensure the desired interests remain. You can see from the Ruby site that it's less than 5 posters just going round and round the same tired old topics.
It's not about it being right or wrong, people are free to like whatever they want for as long as they want but it's just human nature for your passion for something to fade over time. Whether you play the game 10, 20, 30 times over, there will come a point when you have had enough.
When that point comes, it doesn't make it bad all of a sudden, just irrelevant and it's time to move on.

You must not be familiar with metaphors/analogies etc. My cocoon metaphor was just to symbolise isolation, not a resemblance to an insect.