Newish to this site. How long has this been around?
I have been a member since February, and it was certainly going strong at that time. There are almost 30,000 members, but the number of members who frequent the site and post, comment, and participate in groups is a fraction of that number. If you become active, you'll start to see many of the same members very frequently.
Just from what I have gathered from comments by members, I think the site has been open since early last fall. That is a question for @admin.