OP, there's not a lot that's going to be done, unfortunately. Theymos doesn't really care if people sell accounts, farm accounts, or any of that. If he did, there are many things that could be done, the most obvious of which would be to ban account sales on the forum. So I think your suggestion will fall on deaf ears.
Even tagging account buyers & sellers is of limited use, since most people create sock accounts for those purposes. But I still get a big grin on my face when I find and tag a sold account that's being used to spam. If you find one that's obviously been sold, drop me a PM.
Actually it is hard/impossible to stop without any form of KYC whether it is account sales or account farming. Forum do not do KYC (no online forum do as such). But forum can take phone numbers to be linked with account but still I guess there will be cheap SMS service will be started somewhere to assist in registration.
As they already put in rules if they ban sales in this forum then it will happen outside the forum.
The root is "bounty money" involved in this forum. I think "Altcoin Section" can be separated to another forum but still it will not help as such as advertising deal will be done outside of this forum to advertise in this forum.
In short ," Money attracts evil". Until and unless this is not solved, efforts to clean the forum will always remain in vain.