I use both - web forums and Facebook groups - in pretty much equal measure and cross-post my content to the relevant groups/forums. Some (of both) are better than others, so over time I've dropped out of some forums/groups which became less relevant to my interests or which imploded for whatever reason.
With Facebook, you don't have to post every detail of your personal life to join and take part in the groups, I know a few friends who have a fb account solely to contribute to the (better) groups. The fb groups are searchable to fair degree, by layout name, user or subject and there is a lot of useful info, photos and discussion across them.
Very niche-interest forums, in my experience, often have a 'shelf-life' and die without regular new blood (members and things to discuss).
There are also still email groups around, groups.io took on a lot of the old yahoo groups when yahoo pulled the plug - I'm in a couple of very active egroups with daily post count into the dozens.
The more transitory systems (tiktok, instagram and twatter) I've never bothered with, but the 'yoof' do and apparently that where they post their railway interest content, both prototype and model. Perhaps, as a wider hobby, we shouldn't just dismiss them and risk losing 'the future of the hobby' simply because we don't like/understand their preferred outlet?