Buying of accounts was allowed in the past, but it’s currently highly discouraged due to the high use of the account for spamming. The restriction that could follow with such an account is that those earned glory in the past by the account owner, i.e., the trust built based on the old owner's reputation, are likely to be revoked. If people notice that the account was bought, a few members will tag the account, warning people to disregard their old trust rating.
Buying Bitcointalk account is still allowed. It has been discouraged right from the beginning. Accounts that are not bought can be used to spam, but bought account can lead to scam. Not only that, the buyer can be scammed, the account can later been know for bad deed like plagiarism and be banned. That is why account sellers are given red trust. It is also not just good not to have the experience but just buy an account and post like newbies or later be banned.