So often is the case when dealing with cheating/botting/unwanted behavior/etc. revealing information only makes the problem worse by informing those parties.
We know that people bought gold to use in GDKP’s. Were there innocent people in GDKP’s? Of course but they were being fed the bought gold.
In all aspects of life, cheaters ruin it for the innocent. In this case, I’d much rather disrupt the bots and lose a small avenue of gameplay. Without any stats to back it up, it’s obvious the bots will sell less gold now because there is less things to use gold on. The same effect would happen if they removed repairing gear from the game.