I think most of the time people can stop it simply by putting their opinion into the scam threads as they come across them.
We all have verbose opinions and love to type.
If most people took a few seconds to identify the scam thread as they incidentally come across them by posting so in them, those threads would quickly fill with scam warnings.
Then we will have done all we can to protect our own reputations, because the scammers naturally try to mascarade as us, the non-scammers, and affect the reputation of this whole forum.
We all have verbose opinions and love to type.
If most people took a few seconds to identify the scam thread as they incidentally come across them by posting so in them, those threads would quickly fill with scam warnings.
Then we will have done all we can to protect our own reputations, because the scammers naturally try to mascarade as us, the non-scammers, and affect the reputation of this whole forum.
People constantly try to warn others in threads where likely scams are happening and get told to "stop trolling".
The scammer forum is pretty much for after the fact warnings and having glanced at the crap it's filled with now, it's become pretty much useless.
Introducing a post/time threshold for certain types of posts would increase the effort required to start trolling for victims. I'm hesitant to use SomethingAwful as a reference point, but the requirement that you must be a member for 7 months before you can sell something on their SAMart forum helps make scammers look elsewhere for easy pickings.
You're not going to stop scammers looking for victims. You can only exert some measure of control over how easy it is for them to find them here.