For the record, I have played a number of other MMO's and am well aware of their multi-boxing policies.
The point is, Trion are trying to be different here and they can't simply say, other MMO's do it so we will too, when they've been so publicly against automation recently.
Let's look at the way they've rolled back toons, placed bans and even removed plat from players fish botting. It's an unfair advantage so action was taken.
If one person is pressing buttons for one character yet software mimics those actions across another four characters, say while fishing, he is also gaining an unfair advantage in making 5 times the profit he should be for that one action.
It's not rocket science, of course Trion looks the other way when people are paying for legit extra accounts but there's a huge difference to playing an account on it's own and playing an account and having 4 others play automatically.