Is it just me or does this sound oddly familiar to machine learning recommendation systems? ie: show an item based on the average of all the other items that everyone else has looked at.
For example if you employ 1-nearest neighbors, you will actually return a sample that is guaranteed to reproduce another user's preferences. You could of course sample over more neighbors, smoothing results, at the cost of more lookups and at some point in the limit you do see reduced performance due to too many points becoming similar and having this average of everyone being bad for everyone sort of thing. Most ML approaches account for this and will only look at user/item clusters where the assumption is that a user can be sampled from a user cluster and an item can be sampled from an item cluster. Locally you may have error incorrectly capturing the clusters but in practice this works fairly well and you dont have a one size fit all model.
If you're thinking about the cold start problem when you dont have any information about a user, yes it's possible that your overall statistics is a combination of many subpopulations that doesn't really fit anyone very accurately but there are ways around this as well.
So in short - a naive ML recommender that perhaps you get out of a textbook would certainly face these issues but the are addressable in production with an "industry" grade recommender system and will lead to better performance. I don't have firm numbers but in A/B/C tests compared to other black boxes I've seen 20-30% better performance when you start to address some of these issues.