They do still exist, I have a specific but popular vehicle, and there’s a dedicated forum style site directly from 2011.

In a perfect world, that would be folded into the “fediverse” protocols, but like they’re already paying their own hosting etc. In the end that’s all reddit did: absorb some nominal hosting and IT for exposure. It made sense for hype niche communities, which is how reddit grew, but now that they’re killing control of the communities… Well… It turns out people were willing to pay for those servers back when they were expensive…