To be honest, very less people's using self moderated thread to prevent spam. Most of use self moderated thread for manipulation. On the other hand, one of main scammy activity is, "sell on lock thread". Those users try to sell by locked thread that means there is something wrong, and personally I believe that kind of behaviour is one of symptom of scam.

However, I am not fan of self moderated thread but it would change based on user rank. Self moderated thread should be disable below full member rank.