The analogy is spot on contrary to your assertion otherwise. Cook isn't comparing the iPhone to Best Buy he's comparing the App "STORE" to a Best Buy "STORE". The fact that one is a digital marketplace and the other is brick and mortar is irrelevant. All the rules and consumer laws that apply to selling goods in a brick and mortar STORE apply to the App STORE.
You can buy a copy of WoW at a Gamestop or you can buy the digital version directly from Blizzard. They are the same thing despite one being brought in a brick and mortar store and the other online. And guess what, Gamestop can't be forced to lose out on sales by being required to put a sign up telling customers they can purchase the game directly from Blizzard which is what Epic wants Apple to do.
Additionally, I have never subscribed or played any online multiplayer game where I didn't have to provide a valid email address. There is absolutely nothing stopping Epic, or any other developer, from sending promotional emails to subscribers to suggest they renew their subscription directly on Epic's website. The only prohibition is that they can't do that promotion within the App Store itself. Which begs the question what type of lousy marketing department does Epic really have that they can't convince the majority of iOS players to renew subscriptions / make in game purchases directly from their website.
Epic wants all the benefits of the App Store not only for free but without having to do the basic work any reasonable company would do to promote direct purchases.