Maybe it would be better if we could propose to the forum to ban trading accounts so that if someone buys an account then it is clear that it is a violation.
You can't prevent them or prove them all the time. As long as the signature campaign is here on the forum, account trading will be there. How will you ensure an account isn't traded or traded? theymos doesn't want to give a false impression since it's impossible to track. So, it's better to be with the current rule. The feedback system can fight with account traders nicely.