Please also consider this from the GMs' point of view: is it honestly even possible to stop account selling? If people want to trade accounts under the table, GMs really can do nothing about it as GMs' powers are limited to ingame and forum only.
The most GMs can do is not to allow the public broadcast of announcing these sales publicly, which I guess is what the OP wants... but if people really want to sell them, they can do it under the table and it's pretty hard to detect and prevent.
