Goldsellers are like the tabloids, they already have the budget for ban.
1 banned for 1 new account, it is a problem that MMOs manage more or less well.

In WoW, the additional QoL solution, people you post are also mute the time of your active connection, if you are disconnected, you see them again.

So what can an MMO do for goldsellers who in the time of the CD/DVD, they already had a pallet of license in stock in case of ban ... Today a license is bought online. There is no miracle solution, just solutions that could improve the QoL of the players.

To say: "Fed up with goldsellers/bots" is like saying "Fed up with crime"; as long as there is money to earn easily/quickly, there will be.