I'd be surprised to hear they were selling viewing data though. A few years ago, they were making a lot of noise about how that data gave them a unique way to make decisions on what content to produce that other studios lacked. Seems like the kind of thing you'd hold close if that were the case.
When you search, it's also clear they have shadow profiles for content they don't have (e.g. before they had Monty Python and the Holy Grail, they'd autocomplete to "Things like Monty Python and the Holy Grail" pretty early in the autocomplete results). I wonder how heavily that search data is weighted in deciding how much to offer to license existing content.
Probably quite highly, as it’s well known that Netflix also watches what’s popular on torrent sites to help decide what to licence next.