Oh God I remember that story. I didn't remember it being Buffy but I definitely remember the part about a web forum with dozens of maybe hundreds of users arguing with one another who all turned out to be the same person. It's basically the most well-recorded game of Barbies in history.

That one wasn't the Buffy board, which was actually used as a news portal rather than a discussion forum. I want to say it was some kind of wedding planning forum? https://www.vice.com/en/article/the-forums-with-only-one-user/