Multi-boxing may not be a RMT exclusive action, but it is still highly unfair to other players. Just by running leves that player is multiplying the gil rewards. If he is using automation software to do crafting or gathering he is once again, multiplying the feasible income.
Multi-boxers may not be trying to sell gil, but they will still be a negative impact on the community because of how easily they will acquire materials and cash with only a fraction of the effort.
Besides which, allowing them to do this and use the 3rd party apps needed to help them play the game with 7 other accounts just gives RMT more leeway to the same and claim "I'm not RMT, I'm multiboxing so you can't ban me".
Multi-boxing should not be allowed in a game like FFXIV.
