What I don't understand, so much enthusiast discussion has migrated away from forums to FB, but FB is a terrible platform for enthusiast topics.
Like cars, for example. Many of the car forums I am on are basically "dead", the consensus is all of the discussion has moved over to FB. But, FB is a dumpster-fire, it's not conducive to organizing enthusiast thoughts/activities into a searchable, logical database.
My best guess as to why is since your average person already has a FB account already and if they had to pick between making a new account and joining a forum or joining a FB group they opt for the latter. The same applies for Reddit, especially for enthusiast discussion that caters more to the 18-30 demographic. Kind of unfortunate in my opinion as forums present the information to you in a much more searchable and organized manner compared to a FB group or a subreddit. I guess FB groups and subreddits are the modern day equivalent of Yahoo groups. I remember there used to be at least a couple of them to discuss streetlighting.