on a concrete level, a forum takes bandwidth and server space. some search bot is always trying to crawl every little corner for information, slurping bandwidth as it goes.
phpbb spam controls are awful. it's a very common platform, and a million spambots are trying to get in, the registration page is always the busiest. I had to turn off registration a year or two ago and just tell people to email me if they wanted a new account. I know that's awful, but every patch I put in eventually became useless, and spambots would make dozens of new accounts a day. We had questions and administrators approving accounts. It was just terrible.
laws always get more complicated. they are made with good intentions, but they are made. privacy laws, the cookie warnings, data protection. heck, it started in 2002 with COPPA. The laws are made by lawyers. I do not have lawyers. I am a small, independent web designer. So it makes me nervous. It's easier to just back out. Back away from anything that people sign into or give information.
Some parts of the site are still used and still helpful. The pregnancy/due date statistics, the mnemonic generator, the skirt pattern calculator. they are more grown up.
I will remember the forums as a source of great joy for a long time. I don't know why people flocked into it or how we attracted so many teens! there were thoughtful, brilliant members who shifted the culture in the right direction, who battled trolls like dragons! we were the top feminist forum on google for a while, that attracted all kinds, and not good kinds, but we had great rules for dealing with them. we were tolerant, but only to mess with them for fun, when they weren't fun we banned them. meanwhile the teenagers who came for useless quizzes would see all this go down and maybe, just maybe, absorb a little.
maybe we, as a forum, came to a consensus, and we were done. the internet changed and everyone moved around and it wasn't the same. but it was always there and any changes we made to people are always there. so with that thought, I said okay, thank you everyone for coming! and closed the doors.