First, few people will put in effort into understanding their friends' psychology and habits to use Netflix effectively. We shouldn't optimise for such users.

First, few people will put in effort into understanding their friends' psychology and habits to use Netflix effectively. We shouldn't optimise for such users. Second, I don't know whether individual ratings should be normalised as you say, but the final rating that's displayed should be normalised. For example, the app stores should have 20% of apps rated five stars, 20% four stars, and so on. This will make the ratings more objective and easy to understand. If the average rating is 4, then an an app rated 4 is merely average, which is counter-intuitive. (Perhaps normalised within a top-level category, like Productivity and Games)