The problem is that warlock lack a melee ability that can properly use the perk. Worm gods gets a lot of use because it can be used with hammers which can be thrown endlessly. Warlocks do not have a melee ability that can be chained in a similar fashion. Once you hit your melee ability and get to the point where you have more stacks you are just hitting with the base melee. Even with the damage bonus that winters guile gives it is still only buffing the basic hand slap. I would have to test it but I doubt that the damage is anywhere near comparable to a titan using worm gods with a throwing hammer

Thats because titans have abilities that allow them to properly take advantage of this unlike warlocks.