One Tumblr you might try searching is the aptly-named olderthannetfic (AKA franzeska—-you’ll note her very low serial number, as a founding mother of AO3—-and franzeska); she hosts a lot of meta and fandom history discussions, often accruing great sprawling fractal link lists and involving fanlore, and has quite likely reblogged the post you’re looking for at some point.

In fact, give me a moment: would this be it? (If so, the “horses” actually alluded to a famous wank/weirditude meme.)

https://fanlore.org/wiki/The_good_old_days_before_google_were_dark_and_involved_horses

(The original, on LiveJournal: https://seperis.livejournal.com/801880.html)