They see a 105 page long thread called Mafia Administration and switch off,
I got reminded of this today. I think forum users' brains become trained to ignore threads with many pages. Just like they ignore STICKY threads.
We have a forum game running for almost 5 years now. https://www.gog.com/forum/general/guess_what_im_playing_forum_game/page1
Was very busy at the beginning, now fairly quiet, but we still get some action and once every couple of months a new face joins.
Today, I accidentally came across a new thread of exactly the same idea (down to the same reason it was brought up - users posting questions without specifying a game). https://www.gog.com/forum/general/guess_the_game_text_edition
Started 3 weeks ago, it has got around 15 new users - same users who saw the old thread popping up regularly but missed it because it had 100+ pages.
It's an interesting phenomenon. If all traces of GOG Mafia disappear, and someone comes and starts a new thread about it, we'll probably get many new users.