I was on a lot of them 20-ish years ago. They all shutdown with the advent of Facebook Groups. I tried spinning up a Facebook Group to keep the crew together, as we had talked daily on one of those forums for nearly a decade, but it didn’t see much action and died out.
A friend tried to start a new forum a few years ago based on his current hobby. It had some decent traction and even led to in-person events, but seemed cyclical based on the season, and I noticed about a year ago he shut it down.
I’m currently on one old school forum, but I’m not super into the niche, so my visits are infrequent.