In some marketplace sections there are restrictions for only members to be able to view.
Given this suggestion, it has been requested many times in the past.
Furthermore, post count does not make a difference.
For all that matters, someone could spam up to 200 posts, and then scam another member.
In addition, there are many other possibilities of users having the capability of scamming.
Whether it be scamming under their own identity, or under an impersonation, there is still a chance.
There has also been history of users beyond the post count of 200 scamming.
Moreover, there have been stories of users working as a team to scam, which is ridiculous, but unfortunately has happened.
The suggestion of a post count requirement to view the Marketplace has its positive aspects, but at the same time has its flaws.
Unfortunately, there will always be those cunning scammers, but the recommendation is to take certain precautions from being a victim of scammers.
Use Middleman. Do some research before you trade with a member whether if they are new, or veteran members. Verify who you are talking with.