i think they don’t want to do it. banning accounts looks bad, looses customer confidence in there product.
but:
on the extreme scale, because they are the ones selling the items (heard this alot, some devs are the ones running the RMT sites)
on the rational scale, its how some players enjoy the game, farming items to sell, or to trade. they need the ability to trade loot in a Looter APRG or it looses alot of sway
on the shareholder scale, inflated account numbers for all those BOTs and when/if they get issue a banwave, a re-buying of those accounts again. also keeping item/gold farmers logged in to “fluff” the player count
on the bug exploit scale, QOL is huge for repetitive game loops, take out to much QOL with a bug fix and youll loose returning players… wouldnt be a diablo game without exploits…