actually it could be used as an incentive to keep members of each faction from getting in trouble and obeying the rules.
i once heard it, recently and from where i do not remember, that dark is not necessarily evil (recalls from where it was now, a Let's Play series done by HCBailly on FFIII for the NES), but rather they use less "holier" methods of making sure the job gets done.
this does not mean they break the rules to do this task, but rather choose a darker art form to bring about the same result, or perhaps even better result
anyway, the advantage would be to give away "small" prizes to members of the side that had the fewer members in jail/or were banned (which the numbers really shouldn't be all that large anyway as most of your jailed/banned characters are botters) for that month, and only to those people who participated in ToH.
Something of this nature would bring a cause to rally new recruits and make sure to train them up to not break the rules and even participate in ToH to at least get something out of it even if they didn't have enough points to get any of the ToH prizes.