Everything kind of fractured apart and now those niche communities are building up again elsewhere.
Discord has a lot (looking at my discord I see, gaming, programming, clothing/fashion/aesthetic, language, dnd, music, keyboard / hardware, dance, etc... communities).
I've noticed a lot of the major reddit communities have matching communities in the fediverse, specifically the ones with old reddit-like UIs. (lemmy.ml, lemmy.world, sh.itjust.works, mander.xyz, etc...).
I've also noticed a lot of web-standards / browser developers and some gamedevs moved to twitter-style fediverse sites (e.g. mastodon.social, indieweb.social, infosec.exchange, hackyderm.io, floss.social, fosstodon.org, etc...).
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I think the fediverse is working well for the niche communities for three reasons:
- Having that little bit more initial friction to learning how the fediverse works has made it better since it keeps out the low quality spamming users.
- Niche communities can only grow organically within their own spaces (since forcing them makes them seem inauthentic).
- The big plus of the fediverse is being able to follow/interact with users/communities across the boundary of being on another website. So it doesn't matter if a niche community you want to follow springs up on another website, you can follow them and participate from the website you already use.
For example: the old reddit-like communities that I follow (listed above) appear in a single feed in my programming.dev account (since that's the first one I joined), and the old twitter-like communities I follow appear in a single feed in my mastodon.social account (since that's the first twitter-like one I joined).