Maybe you want to eat healthy, but that desire doesn't mean squat if you always end up buying fries on the side. Then the health store is better off pushing fries every time, even though you told them you don't like fries.
I used to work at outbound phone marketing (I regret it too), and whenever we were asked to take people off the list, they were kept on, because the marketing company was a dick and because the pool of people who asked not to be bothered again would still contain buyers for the next marketing push.
So knowing better than your customer is hardly a new big data thing (If you'd asked people, you'd end up with faster horses)
Personally I have only watched 1-2 movies from my netflix "My list", so it is hardly a wonder why it is not featured prominently on my netflix page or why those movies aren't used to indicate my suggested content. I know what I want to have seen, but that is not the same as what I want to see.
There's what people want, and there's what people want. The big assumption in the industry right now is that "what people REALLY want isn't necessarily the same as what they SAY they want".
But isn't that dreadfully cynical to put the emphasis on the "really want" side? Like - I want to eat healthy, but if a bowl of crappy chips were put in front of me, I'd probably eat some. That doesn't mean I don't want to eat healthy, though. It doesn't mean I REALLY want chips.
It's really just that they're invested in serving our urges rather than what we think of as important.
Think of it as our "better selves" versus our "worse selves". Couldn't they also make conclusions about what are better selves are, and suggest that sort of content?