[timbeccue]

Do recommendation algorithms not take this into account already? Perhaps privacy policies make it harder to automate this effectively.

[bombcar]

The famous ones may, but it ends up taking into account "what do we want you to see/listen/look at" much more into account.

[ghaff]

The original Netflix prize also, it turned out, wasn't really implemented for a number of reasons. But one of them was apparently that Netflix doesn't necessarily want to give you the best recommendations; it wants you to keep your subscription. There's certainly some overlap between those objectives but they're not the same thing.