Bay12 is interesting though, most people say that this is a pretty mature community. So I wonder what it takes to outgrow this? Any old regulars willing to come back from the grave to offer a perspective?
To specifically outgrow B12? Normally it's just life things ... the time constraints of having a regular job, group of friends, partner, maybe children, and perhaps church (or bowling league) and volunteer work on the side. And any personal projects.
Additionally, the website isn't "sticky." It isn't run by the algorithm to purchase your attention. People just post what they want, mostly text, especially now that free image hosting isn't as available. So, if you aren't thinking through it (and maybe even after thinking through it), naturally almost any other site is going to seem more "exciting" than the old DF SMF forums.
And finally: so many people I knew have left here. But the Mafia oldheads who came up with me are still here, and to run the reading threads and things in a more friendly environment than like Goodreads or Storygraph. It's a perfect site for the kind of stuff that I like to do.
I'm probably still here because I refuse to use any of the big social media sites and am not eg married or part of a big community IRL. I use Discord but not eg Facebook, Instagram, Snapchat, Tiktok. These things are fun but I had a big change about ten years ago when I read every book I could find on social media tracking and committed to going a different way, even if I had to suffer for it.