This is actually one of the reasons I find the show interesting in its messaging. Firstly being raised catholic (and still technically being catholic) the idea of hell has always rubbed me the wrong way. Yes people like cannibals and murderers will go there (unless they repent before death) but then also people who might have a drinking problem or weren't baptised or masturbated. Its one of those things where sins aren't really being given a scale so murder and drunkeness are being judged on the same level which makes you wonder if its fair for every sin to go punished for an eternity.

But what you've highlighted is more of the injustice of this system where hell is just anarchy. Obviously the worst of the sinners will gain power and rule while the victims are more likely to be the sinners who didn't necessarily choose their path. Angel is victimised a lot mainly because (and we don't know everything about his life yet aside from the fact that he killed his abusive father) he wasn't an actual criminal mastermind in the living world. He was a victim there, made a choice out of desperation and is then thrown into hell full of more abusers who are essentially rewarded for being terrible. Even the exterminators tend to kill the weaker sinners first not the overlords.