I'm not following this completely though. So you fragment power among different subdivisions of a government still run by evil people, in the name of using these fragmented subdivisions as checks and balances against one another. Presumably the subdivisions are each strong enough to govern those not in power (a prerequisite for a government in the first place; I could deem myself the arbitrator of justice in America right now, but I don't have the strength to enforce it) but weak enough that none could overthrow the others and establish hegemony for itself.
Why would the empowered subdivisions care about fighting one another, though? I would assume from this situation that they would perpetrate evil against the humans that don't have power and try to stay away from costly struggles against other subdivisions. Think of the Concert of Europe, for example, where the great powers delineated spheres of influence and tried to avoid great power-great power conflicts. (That the system collapsed is, at least for now, beside the point - just drawing a hypothetical example based on a real-world situation I've been thinking a lot about lately.) Within their spheres the great powers weren't going to be impeded from doing roughly whatever they wanted, as long as that whatever didn't lead to them becoming powerful enough to upset the balance of power.
Or the hypothetical world of 1984 (ignoring that it's anti-communist for a bit and focusing solely on the three great powers as authoritarian states, not necessarily with any specific ideology) - where obviously, rather a lot of evil was carried out by the government of Oceania against the citizens, but without that being an impetus for Eastasia or Eurasia intervening. I would envision such a scenario reaching an equilibrium like one of the above, where your empowered evildoers enjoy hegemony within their specific areas - "enjoying" it by perpetrating evil against those not empowered.
And, again, I'm not arguing that the no government alternative is any better, here. Whether or not it is would be mostly inconsequential: in either case, life would suck for the vast majority of people. Which is precisely what one would expect from a world of evil assholes.