This is Meetup.com. (Or was before the pandemic; most groups I've looked at still haven't resumed, and who knows when the hysteria will ever subside.)
It is easier to find people that share your interests and make them friends, than to make your friends share your interests. Meetup and perhaps local Facebook groups are the way in to that.
Meetup is great for users, for individual hosts it's way too expensive. I can't view the current pricing, but my small group closed after I got tired of paying $90/6 months for a glorified email list + calendar.
For companies that's chump change, but for a casual interest group it's too much.
Tried to migrate the core members to Facebook groups which is free, but there wasnt enough interest to keep it active. Friends with a few people still from it though.
Meetup is key for discoverability. Both because Meetup is where people actively go to look for something, and because they may incidentally see your group/event while doing something else on Meetup. There's nothing else that gives a group local findability quite like Meetup. That's what you're really paying for, although agreed that the price is an obstacle.
Also agreed that migrating to Facebook usually doesn't work. In any group, there's a quarter or third or so who refuse to use FB, and that tends to kill your critical mass.
Meetup events (at least the ones I've been to) seems to be coming back online (UK Brighton area). Shameless plug for Flock #10 for anyone around Shoreham - one of the reasons to like it is the "No Selling!" rule.
It is easier to find people that share your interests and make them friends, than to make your friends share your interests. Meetup and perhaps local Facebook groups are the way in to that.