You might find more if you (as an admin) did a low-level search for users who included links in their first 2-3 posts. Obviously most would be false-positives, but it could be a fun game.
I did some moderating of a popular FB group for a few months. The group was the target of huge amounts of spams and bots, and a bit of general tomfoolery. I got it pretty well cleaned up, set up rules, etc. It was an interesting gig, until it got tedious, and I found out I was really the only mod doing anything. It was many hours each day of active monitoring, and going through huge piles of requests and posts. I know a lot of the long-time members appreciated the work, but in the end I was tired. I stopped moderating, and left the group, and I know it fell right back into disarray.
I appreciate you guys for what you do, and the amount of time you volunteer to this site.