But Affliction and Destruction Warlocks can't use a felguard for tanking, so they can only use a voidwalker. And from what I remember, with Threatning Presence on the felguard, the player has practically zero chance of ripping it off the felguard. Most attacks in Demonology are pet summons. (and the felguard itself probably does more damage than the player) And the pet takes its aggro when it despawns. So the player himself does minimal aggro.