I've always been really fascinated by obscure communities and websites online. There's something really satisfying about a website that isn't part of a larger conglomerate.
While the rarity of IRC, forums, and niche informational websites has risen dramatically because of the rise of centralized replacements run by huge companies (Discord, Reddit, Fandom respectively), there certainly are still dark(/light?) corners of the WWW where real discussion takes place on the same decentralized systems the internet was raised on.
Last year, I tried out tilde.town, a multi-user linux system with a focus on community and creativity within that community. I found it refreshing to randomly browse the intranet there and see what users have created, and the experience and interactions really reminded me of some of the forums I used to participate in.
Through much of the mid-to-late 2000s, I spent quite a bit of time finding, joining, and participating in obscure communities- online games, forums dedicated to extremely specific topics, IRC networks, etc. My favorite times were joining communities that had been alive for a long time, and had just a few dedicated members who kept the activity flame going. Seeing that dynamic was really quite interesting.
I really think it's quite a shame that the popularity of open systems like IRC, decentralized communities like specific niche forums, blogs and infodump sites ran by average joes, and everything else in-between has waned so much.
Part of the problem is almost definitely a global reduction in the amount of free time spent navigating and taking part in those communities. Maybe it can also partially be attributed to obscurity via scale mismatch - there's just so much else out there now that it's even harder to find these islands, in spite of their continued existence.