In my opinion, DT members should agree among themselves on this matter to prevent controversial situations.
All DT member's opinion could not be same, and feedback's are not moderated by DT community. Someone even not agree to tag account sellers, so what can we do? On the other hand all cases judgment wouldn't be typical. Sometimes I am tagging account sellers but it doesn't mean I should tag all of them. I might have my own judgment strategy and perhaps other DT wouldn't like my judgment. So I don't think we can come conclusion about tag account seller.
Why it is not said here.
"have multiple accounts and selling accounts is prohibited in the Forum".
Because it's not possible prevent create multiple accounts if there is no KYC. And theymos will not do it ever. Users might create multiple accounts by VPN or whatever.