The fact that account sellers need to keep their products from being revealed is 100% the result of the fact there are dozens of people on this forum who feel it is their right to go around policing the forum by whatever arbitrary metrics they deem valid rather than the forum rules.
Scams are not against the rules either. Actually most if not all use cases for the trust system don't have anything to do with forum rules, which are enforced by moderators. Untrustworthy actions are often done in secret or otherwise obfuscated. Exposing them is not a red-flag offence.
Edit: Since it appears everyone wants to use analogies, let me use this one.
Don't even need to go that far... as I mentioned above, just selling green trust appears to be fine in this newfangled interpretation of what is considered a legitimate "business" or "property".