This topic is brought up way too often and the conclusion is that admins/mods can't stop the black market trade of these accounts.
That point does stand, however the situation would be different. When you think about it, right now there is nothing stopping you from involving in these trades (there are no 'risks', apart from possibly getting scammed by either the buyer or seller). In the case where account sales were disallowed (a bannable offense) there would be no more sales on the forum (they'd have to try to engage in these trades somewhere else) and now a certain risk factor would be present (anyone who gets caught doing account sales would be permanently banned). This would reduce the amount of trades by a noticeable amount.
This would also have a lot of unintended consequences.
It would cause the prices of accounts to fall dramatically, which you will say is a good thing, but you will fail to consider the fact that this will make it cheaper for a scammer to attempt to scam with a purchased account and will lower the threshold that a scammer will need to steal before buying an account will be NPV positive for a scammer.
If a purchased account is going to get banned once it is found out that it is purchased then it will quickly have zero value. The problem with this is that this will encourage people to scam with a purchased account because if they are caught trying to scam, then the negative trust they will receive will likely have zero effect on the value of the sold account. As it stands now, if you buy an account, use it for whatever honest purpose then you can potentially resell it for something of value, and if the account gets negative trust then it will lose that value.
It will cause people to become more complacent and trusting of established accounts, which would make it easier for scammers into tricking people into sending btc/things of value without taking any kind of precautions.
All of the above will also encourage people to scam via buying accounts, which will only exaggerate the above problems.
Typical loggorhea from quickscammer. By this logic there would be less monetary incentive to farm accounts, and that is a good thing. But we don't really know until it happens, do we? And until then, as I have argued before, account buyers and sellers should be negged till it hurts.