I hope sites that just provide a way for people to assemble offline will be the new thing soon.

A photography guide's site that rallies amateurs for walk tours. A planning board for a foreign language practice group. A site with a schedule and registration form for a sports event.

When I read "online social" my head thinks "not-really social".

I'm working on a game that helps with this. You leave your little bunker in a post-apocalyptic world and find the land around you contaminated. You walk, run, any workout, to claim territory around you, and gain energy you can use to clean up. You start building greenhouses to grow food and start rebuilding the ecosystem. It's all on the real world map underneath you, and all the interactions between people in the game are cooperative: you get more benefits helping another player with most actions than doing the same thing in your own territory.

The game tricks you into going for walks or runs regularly since you need those energy points for everything, and I'm building out more cooperative behaviors to give you reasons to go walk with someone else, go work together to fight an alien infestation, and more. You'll discover other players in the game who are near you in the physical world, and be able to request help, thank them, give them benefits, all positive.

I've learned a lot from Niantic's strategy, but they've never leaned into actually helping people improve their fitness, or work out together. I'm hoping I can help solve this problem you're talking about, at least for getting people fitter!

Meetup used to be that until they got greedy and started charging everyone. It collapsed very quickly after that. It's a ghost town now.

Yeah, the internet was originally an extension of the real world, and it probably should have stayed that way.

Ironically in real life most offline activities of these kinds that I know of are facilitated on Facebook groups.

mom&pop social media is the old thing, and like other mom&pop things that got steamrolled by their equivalents of Walmart, it is highly unlikely to ever return.

95% of people choose utility and convenience over ideological preferences, and that's not necessarily a bad thing. I too miss the old Internet sometimes, sure, but I'm not ashamed to admit that I'd much rather deal with anonymous strangers or LLMs than ye olde phpbbs with their anal moderation, resident schizos, and weird cliques.

If you’re into running, cycling, etc. Strava can easily function in this way and does. I’ve made a bunch of friends and been introduced to groups and routes through my interaction with initial strangers

That already exists. It's called social media and people promote real life events there.