It seems like tags might be a better solution to classifying music than over-broad categories like "rock".
Making genres more specific and granular just makes categorization more confusing and contentious. But use of multiple tags to categorize a song could allow different people to simultaneously apply the labels they prefer.
Or perhaps a better solution would be "x sounds like y, z, etc."
It seems like tags might be a better solution to classifying music than over-broad categories like "rock".
Very much so; I've lost count of the number of times I've wished that players would recognize more than one genre tag; heck, even allmusic.com had multiple "styles" for their listings.
Of course, the real problem is human language, it's subtleties, and how people (ab)use it.
These genres come from people talking about music using whatever organic / natural words they use to describe music. We've done the work to map those into single-term "genres," as it's been shown many listeners appreciate the flat categorization. There are similarities between genres in the API, so you can quickly see which genres sound like others.
But Genres already are, effectively, tags. Depending on implementation, artists, albums or songs are given one or many genres.
If by tags, you mean user-driven categorization by arbitrary text, that's an even harder problem. Tags can be spelled differently and mean the same thing. Or they can be spelled the same and mean completely different things. What you mean by "punk" and what I mean by "punk" are different. Possibly radically different. If tags are to be useful at all, you still need one authority who decides specifically what each tag means.
Some bands cross genres quite comfortably. One of my own bands does some material that is basically "If Lilith Fair had a prog band" (so both progressive rock and "Lilith"), but other material that is straight up parody in the Weird Al style ("filk" or "dementia", neither of which I found on the list).
The problem isn't with genres, it's with trying to put bands in them.
Making genres more specific and granular just makes categorization more confusing and contentious. But use of multiple tags to categorize a song could allow different people to simultaneously apply the labels they prefer.
Or perhaps a better solution would be "x sounds like y, z, etc."