it has nothing to do with genre tags, it’s to group artist/tracks based on listening data, we could consider the result is a genre. But really it’s only statistical relationship.
This approach is building a group of track, it doesn’t give a relationship between two tracks has it’s the case in session. Sessions can give a relation with a value that represent how strong is the relation. On the contrary in this case there is not such value. e only know the tracks/artists are in the same group.