Then do the more unique events on a different day (and let members suggest/ organise events too).
Friendship is repetition with the same group. Make it easy on people by meeting at the same time, maybe changing venue within a small area.
A group chat can be the clubhouse these days provided everyone meets regularly. I'd revoke membership from frequent no-shows. You want to limit groups to around 70 people too. Some research says above that cliques form.
I'm sure other groups have that kind of rule too, but the mandatory part is what makes it special.
Those all still exist, right? Or did they die off with the WWII generation?
I sometimes wonder how my grandparents' generation, who were generally hard-working farmers and tradesmen, and who raised large families relative to today, found the time to maintain all those groups along with their churches. Different priorities, I guess, and that was not only before the Internet, but before TV really took over.
If they really want new members, they need to self-reflect on antiquated requirements that might turn off younger people from joining their organization.