While there is some truth in this, it is very likely that an increase in number of users will improve recommendations. The Listenbrainz recommendation system is based on a collaborative filtering algorithm, which generates user-specific recommendations based on the listening habits of users with similar taste in music. Hence, if you loathe middle-of-the-road pop, you should actually receive few recommendations of pop music once these get purged by more suitable alternative suggestions. The problem described in the OP sounds like a typical statistical issue, caused by insufficient data.