Bitcointalk accounts? I think its obvious that everyone dislikes the practice of selling bitcointalk accounts. But I think banning the practice wouldn't stop it at all. Search it up on Google and you will see that they are being sold everywhere and not just on this forum.
Bet365 accounts? Yes. Its fraud because to register an account there you have to provide addresses and I think documents such as identity to be able to place bets. Though I could be wrong on that last bit.
At least by forbidding posts related to the sale of such accounts, we can stop the fraud of these people
if you check scam accusations section on this forum you can see many people scammed by these people just in this forum