From a technical point yes, but profiles are too rough and hard to use for this. What I mean is more some way to automatically maintain a kind of sub-profile, f

From a technical point yes, but profiles are too rough and hard to use for this. What I mean is more some way to automatically maintain a kind of sub-profile, for each different aspect of a user, but exposed user-friendly and effortless. Most people won't maintain a separate user profile just for recommendations, as it's too much work for too little benefit.