CW - you are conflating membership with participation - obviously, if the member has a lot of activity - its a better bet. A new member who just registered last week - not so much.
I don't think so. As far as I am concerned, there is no legitimate reason to join a forum if you aren't going to actively participate. No need to join if you only want to read others posts.
Joining the board just to sell your trains? ...... You can sell them to someone else, not me.