Merit is now quite hard to earn, so someone who cant earn it choose buying account have at least 1 merit to conduct bounty campaign in this forum.
Actually it is not that hard to earn merit, only those who are giving up before trying says like that IMO. Buying account is not prohibitted by forum rules but we users are not recommended to do it especially if the main purpose is for earning money through bounties.
In order to stop the selling of accounts I think mods should ban the ones selling as soon as possible. Most of the account sellers are going to try to scam you anyways, so they can make easy money off naive people very easily if they are allowed to do it here literally on the btctalk forum.
Selling and buying transactions are not only happening in this forum, there are many sellers out there such as in Telegram, facebook or other social medias. It will be very hard to cover it, we are lucky enough to have some DT Members who are so active in tagging those sellers and buyers. I think it is enough if the main purpose if to avoid scam.