Preventing the bots from farming makes sense. What doesn't is that it should be the same for all. There are just as many BOT/MIN bots as there are some BLM. There are a lot of workaround about this issue such as make the flying mount necessary, spawn more fates where the gathering/ killing occur, place the mobs/spots on different level which can be reached by only humans with control of their mouse/controller, get some drops in dungeons, adjust the drop ratio according to the player's level or even according to the weather outside, just like fishing.

Just saying it's meant to prevent bots from grinding is not enough of a good reason to me. Definitely not.