...which really doesn't make any sense at all. It seems a lot easier to just farm open zones for chase loots. If their concern was AFK play, they could just scan logs and see that "oh, this person has created/flipped/cleared this instance 20 times in one day, seems suspicious". If anything, as a dev myself, I would greatly *prefer* people farming instances, because it should be technically easier to manage/monitor the lag/load/packets etc, because you are in a pseudo-isolated environment.
If I had to guess, I think the line of reasoning was simply "If AFK players want chase loots, they will have to risk being seen by other players who may report them". Or most likely "Players creating instances cause extra burden on our servers - do not reward this behavior."