That's not true. It was just bespoke. The first general-purpose "forum" software was mid-90s per https://en.wikipedia.org/wiki/Internet_forum but initial one-off implementations grew out of the BBS scene that goes back to the 70s and 80s. They were pretty universally crappy, and just north of "guest book" comment lists, but they did exist.
That said, enough of the early stuff in here mentions newsgroup that it was at least seeded from Usenet. By 2000, though, Usenet was essentially dead for actual communication use so I'm guessing the later stuff in here was done within a forum.
Might not have been this forum, though. It's on phpBB, which only goes back to 2000, and more tellingly, the domain was registered in 2012.
I'm impressed, TBH. The bottom really dropped out of Usenet when it started getting used as a file transfer mechanism, and most conversational traffic moved away from it.
Probably a newsgroup dump in support of some spam or ad fraud scheme.
https://whois.icann.org/en/lookup?name=computer-programming-...