The free ad window was meant to grow the platform. Trouble is potential buyers are turned off by so many cons, frauds, counterfeits and low quality merchandise. A vetting layer that Pundit suggests would knock off half of the merchants - but the overhead is costly. It's pointless to have a platform of bottom feeders.
For instance the landlord should have to list the apartments himself, not some agent who can be a con. He gives title deed, etc, pays a deposit and gets it back only after the buyer reports back. The platform is a guarantor not a website. The buyer details also remain on the record as well. No dark web.