I was on the PDF too for many, many years. November this year would mark my 20th year anniversary there, but i stopped visiting regularly around 2017 since the place was pretty dead at that point (and why i joined this forum!). Posted some posts and pics and hardly got any replies anymore near the end. There was still a group of regulars that were pretty tight it seemed, but besides that not interaction at all.
The forum was 'down for maintenance' for a few months and would check every few weeks, but still got the same message until a few weeks back when it was all archived. From what i remember it were a few people that replied on everything and thought they owned the place, turned pretty toxic fast. Nail in the coffin for me was when they closed down the Chit Chat section; that was the heart of the forum.