alt Hacker NewsI think it’s bigger than a decrease in attendance in religious groups though I agree the impact is felt there too. Social clubs, non-profits, fraternal and civic organizations, neighborhood associations, labor unions, local political chapters, trade associations, etc etc.
Basically all forms of outward focused, community or geographic based groups seem to have been on a downward trend for decades in favor of hyperreal, inward-focused online spaces.
Church is a big thing though, it's weekly and not some hobby or niche. Like I've moved more often than I kinda wanted to, and each time instantly started hanging out with friends I met after church, even though I wasn't going there to meet people.