If account sales are prohibited then there will be no special place to sell accounts in this forum. I also did not find a ban on buying and selling accounts.
It is not prohibited nor deserves a ban.
It is similar to playing soccer in your garden, your parents didn't explicitly prohibit you from playing but they might get the ball at any moment if they are afraid that you will break the window. Well, the bad news is that your parents are always afraid.
I think clear rules are needed, so parents can let their kids play the ball freely.