Well, it's less of a technology problem than it is an industry one. You can have multiple entries in the genre list and they're freeform, for example Ambient;Electronic, in both ID3v2.3 and ID3v2.4. For Vorbis Comments, you have multiple GENRE= tags. Some players support this.
In my interactions with distributors, it seems streaming services tend to support up to two genre classifications; though they're pretty outdated and general (even more general and dated than the Winamp genre list). I don't think they use the metadata presented much in the classification; in fact Spotify does its own estimation of 'energy' and other subjective emotions using various classifier algorithms.
In my interactions with distributors, it seems streaming services tend to support up to two genre classifications; though they're pretty outdated and general (even more general and dated than the Winamp genre list). I don't think they use the metadata presented much in the classification; in fact Spotify does its own estimation of 'energy' and other subjective emotions using various classifier algorithms.