Is it really just a music player? All it does is fetch some binary blob in some audio format and play it?

I feel this is another Dropbox moment [1] on Hacker News where the hyper-smart ones here dismiss a whole technology/company on their most simplistic assumptions about what the product actually is doing.

[1] https://news.ycombinator.com/item?id=9224

There are hundreds of screens in the Spotify app

What you're saying has nothing to do with the complexity of their app.