Facebook Groups seems to have replaced a lot of forums in my experience. The RailUK forum is becoming a contender for the "Things in living memory which seem very anachronistic now" thread.
I have never understood this. You can't have anything like the kind of in-depth discussions you can have on a forum like this, where even one thread may last not only days, but weeks, months or even years.
I am a member of the County Cricket Matters group on FB. It's the only social media group I contribute to and although it has a lot of excellent contributors and topics, it is
vastly inferior to a proper web forum in terms of having an in-depth discussion. In short, if you don't join a discussion within a few hours of its inception, your contribution is barely seen and the group has moved on to the next topic posted.
The only reason I joined it was because the cricket web forum I was a member of was actually extinguished. Its discussion quality for really going over topics properly was so incredibly higher than on a FB page, whether a discussion lasted three pages, or as sometimes happened, and happens on here, 300 pages.
If this forum is becoming anachronistic in favour of FB and other social media comments lists, then we are back-pedalling really rapidly.