The difference is that the communities like that mostly aren’t discoverable anymore like Usenet, web forums and mailing lists used to be, and their contents is hidden behind closed walls.
They don't need to be. Web forums and mailing list are useful when you want to form a larger community with a central idea or project. A chat group is mostly an online hangout place, kinda an equivalent of a favorite bar or a reading club.
What I don't like is when people wants to use a chat group where a forum would have been more useful.
For a wider net, I have a self-curated feed on Lemmy and Mastodon. It's super clean and positive compared to suggestive social media.
The old Internet will never be back, but The Good Parts still exist and can be remade. I don't have to visit the shitty parts.