The technical reason for this is just that the algorithm fails to distinguish between these two groups. Probably its just a hard problem to solve from a sample of what people listen to. I suspect a significant fraction of people that like black swing also like white swing and that results in the algorithm being unable to resolve that there are two features there and not one.
You really need a level of manual curation that a big data statistical model just can't provided at scale.
You really need a level of manual curation that a big data statistical model just can't provided at scale.