I’d have to see the system working before making that call. They say there’s infinite islands within the Shadowlands, but these 4 covenants seem to be the lynch pins that hold the system together, or bring some sort of balance to their realm.
Venthyr seem to be painted in a better picture than the Kyrians. They basically torture souls, but they grant them a chance of redemption, rather than just straight eternity in the maw.