This also goes for the infrastructure around forums - several turnkey sites I tried simply didn't work, and I ended up deploying one myself through a crufty Bluehost portal. Given that a lot of forum activity is driven by non-tech people, I'm not surprised they've started dying out. It's a shame, but the monoliths like FB have both the audience and the on-ramps.
Edit: as a side note, I eventually gave up because I couldn't get my target community to join the forum. Most people were already on a Facebook group and uninterested in switching.
A lot of forums want to not be joined at the hip with a cesspool of transient internet riff-raff which is exactly the problem that platforms that try to cater to everything (reddit, 4Chan) have. It's impossible to have real quality discussion about anything when the people who have deep interest in the subject are outnumbered 100:1 by people with passing interest.
It's not perfect, but it's good enough that it seems to have won the segment by a fairly large margin.
Hmm, I think things like phpBB or SMF are still alive.
I tried searching for this on Google but failed miserably.
He's doing well for himself now, Director of Engineering at a FAANGM company, but it did cause him to abandon the startup game.