Mobile devices killed forums and any medium of lengthy discussion. Most forums seem to have died around 2013 which occurred right as smartphones took off:
Facebook has little to do with it since it's been around for 13 years and was quite popular on the PC.
We've been handicapped by technology and lengthy discussion has been dumbed-down into pithy comments that fit onto a small screen... and coincidentally, twitter.
I don't pay attention to guys coming on asking how to fix their machines anymore. As far as it seems, they may as well be coming to my door and asking for money because I'll certainly get nothing from the exchange. Once they get the help, they'll be gone with no gratitude or anything. In the past, they would hang around a while and post pics and updates on how the rebuild is going so that I at least got something out of helping them.
It was fun while it lasted, but forums are dead.
I have over 5000 posts at atvconnection, but I never ever go there anymore. The only reason I come here is that stuff shows up in my email and I think "ah what the heck."