https://fanfiction.net/ https://forums.spacebattles.com/ https://forums.sufficientvelocity.com/ https://questden.org/ and of course usenet before it. the internet was always built around fiction.
From a perspective of should I link unsuspecting people to a site with a SFW section that can be described as 'vestigial', or maybe 'decorative', I thought "better not." :)