I dont like self moderated topics anywhere. Theyre open to manipulation & dishonesty.
I know there are situations where it can be seen as a positive to have them but if it was up to me (which it clearly isnt) Id do away with them altogether.
Just a personal preference, dont shoot the messenger 
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

Same; You get one person with a wrong conception or stick up their butt and end up with 3 pages of useless posts that are far off topic.... usually if I delete posts on my few self-moderated threads, I will leave a quote reference chain where it ended and delete the rest.... see my xmr-stak thread for a prime example.
However;
I do agree that self moderated threads do not belong in the marketplace section.
Anyone complaining of "freedom of speech" look into the TOS agreement you said yes to when you signed up. Second; this is a privately owned website; not a public one..... don't act as if it is such.