No, you're not missing the point. You're right, Divine Command Theory only follows if God exists and gives commandments. So, those would be other objections to the theory. This objection (That I actually came up with myself!) focuses on showing that in some cases Divine Command Theory would be impossible to follow. One of the main benefits of DCT is usually said to be that no other force has a hand in what is right, it is only what God says. This objection says well there actually is another force, that being logic.