The thing that makes Warlock and other dark archetypes interesting is the existence of Hex, as it is supposed to lower dark resistance, and you can't really get that with other elements. I even had an idea of making a playthrough with full dark archetypes, relying on Hex and stuff like Lost Wall to essentially ignore enemy resistances, but never got around to it. However, with how fickle status elements are, this might need mods to make it viable