You're making an assumption about what you're reporting - that there are bots involved. There may not be. Most crafting can be done in 2-4 steps so even a normal player can craft and list a few hundred items a day. Purchase max retainers, create a few alts and they can sell several hundred items a day.

But it could also be that you're correct and bots are involved. Players have watched marketboard activity for those suspected of botting and the retainers (and Maker's Signature) do disappear after awhile. It's too easy to start a new account, make new boosted characters and level their crafting to max to start the process all over again.

It's not as simple as you think unless you're also going to remove QOL improvements implemented to benefit all players.

RMT and botting will exist as long as players want to cheat games for the sake of pixel prizes. As long as there's a tradeable game currency that helps players get items they consider desirable, RMT will exist. As long as there are rewards gated by content that players find boring or tedious, there will be bots.

If you want them gone for good, you have to get rid of the cheaters. I don't think there's an online multiplayer game with rewards that has managed to do that since online gaming began short of shutting down the game's servers permanently.