Oh yes, I too mourn the days when vBulletin/XenForo/phpBB forums were all the rage, and were packed to bursting with actual geeks you could escape meatspace and nerd out with for hours about your topic of choice. For my child & teenage self, it was LOTR, early Paradox games and Total War up to Medieval II most of the time, and anime/manga to a lesser extent. Discussions were unfiltered for the most part, and certainly nobody would give you shit for being 'problematic' for talking about Tolkien's religiosity & political views or writing an AAR where you conquered the map & exterminated Muslim towns as the Kingdom of Jerusalem. I talked with both kids younger than myself and working men & pensioners twice my age or even older on a relatively equal footing, made my first online friends and got into play-by-post roleplaying on those forums.

Those good old days seem to have steeply declined since 2007-08, and pretty much came to an end altogether with Gamergate exploding in 2014-15. In hindsight that mid-2000s to early-2010s era felt like a perfect evolution of the Internet since Usenet and AOL, where there was truly a place for everyone, everyone could build their own place and the possibilities really seemed endless. Nowadays spaces like those old forums are sometimes still around but have fallen into obscurity (more often than not they have, as you say, gone extinct or worse still - gone corporate), while the rest of the Internet is dominated by these tech giants that want to make 'spaces for everyone' overrun by tranny jannies, corporate shills and ads. Fuck, I'd kill to have the 2003-07 Internet back now.