Belated thanks for the really useful link! I hadn't looked into these opt-out/review requirements before. But, FWIW, I still think there's an important difference between a user-driven opt-out (which I also don't read as a guarantee of explanation) and proactive publication of the personalization criteria. It's still possible for an uninformed individual to never even realize content is being personalized for them, much less pass the threshold of asking how.