I'm in no way denying the benefits that people may find in using these threads, I just think it's a small number within the marketplace. I also am not expecting Mods to begin identifying and fighting scams. I decided to look at it this way, Are they a net positive in the Marketplace?
Probably a net negative imho if we're talking just the marketplace. It seems to be used majorly by scammers in there. Maybe admins should look at other alternatives. What about only certain ranks can self-moderate threads in the marketplace??? Is there any reason to allow brand new Newbie Members to be able to do so especially when most of them are scammers??? I don't think that would be huge inconvenience to new users and I'd say the majority of new users utilizing the feature will just be scammers in the first place. Maybe make users earn the right to self-moderation??? Perhaps make it so you have to be a Member and up. Not so easy to get your account to Member status but anyone can create a new disposable Newbie account which they will abandon if it gets red tagged. Scammers may be less inclined to waste their precious Member accounts and the ten merit it takes to be one.
Self mod topics have been historically effective at curbing shitposts - at least on my threads. So I don't agree with your message messenger. If you were in Sparta, you'd be at the bottom of a well now

Were not in Sparta though are we. Were adult males living in the present day, not some fantasy film shit.
Sparta was real.
Not all of us here are males.
That film was no shit.
Not all of us are adults.
Sparta may have been real but that film was mostly fantasy.