Why doesn't Dirk actually destroy souls? He just kinda relocates them. Isn't that what a Witch of Heart might do?
I mean, the tears Souls right out in a painful and violent way, it’s likely that either he doesn’t have enough power to Destroy Souls just yet, or that the ‘Destruction’ part would come AFTER tearing the Soul out, but he never quite goes through with it. Alternatively though? While Dirk is a Prince, he often acts like a Knight. Emulating Alpha Dave, being of service, and rejecting his ego and the worst parts of himself, so you could say when he puts Caliborn’s Soul in Lil Cal, he’s Giving it to the Doll, Serving his and ARquius and Gamzee’s Souls to Lil Cal.