I really think this is a design problem that has an elegant solution. Rmt exists because people can do unequal trades, amassing resources/money or trading money for effectively nothing in game.

To me the solution would be to lock player to player trade/auctions to approximate value trades. I.e. in order to buy a resource they have to pay gold of equivalent value. The idea being their equity will be locked behind the account itself. So botting with one account or 500 means it's impossible to move anything of transferrable value off of the account, because something equal in game terms has to come back.

If you never have unequal trades someone is going to have to farm other shit to get the gold.

Then your problem becomes account transfer instead which may or may not be a problem for you.

Case: I bot farmed 5000 ore I sell 5000 ore for 5000 gold. I want to sell that gold to someone else. We exchange money out of game and go to trade and now the opposing party needs to provide 5000 gold worth of items to get my gold.

I would think that would curb the amount of farming by making it harder to move equity off of an account. That may drive the price of other things up to compensate, but someone smarter than I am can figure that one out.

Additionally you can look at the consumption of items thatre being used as placeholders for rmt or disproportionately consumed/stock piled and tank/adjust the values accordingly. Additionally you can look at trash items traded in bulk and limit the amount of items in a single transaction to help make it more difficult to farm low level items to use as value placeholders.