Spotify has a point here. And I bet they are not targeting the App Store guidelines in general. They clearly have Apple Music in mind, a direct competitor where the 30% fee on subscriptions is not applied.
I remember the 30% thing being an issue for Netflix as well and they removed the subscription option from their iOS app. As Apple does not have a competitor product for Netflix they did not interfere. With Spotify however they deliberately make it harder for them to offer a great user experience and ignore complaints, because they probably could move many iOS-Spotify-Users to Apple Music if they locked out Spotify.
Oh, and this one is for the fanboys:
- Spotify was there first, duh.
- Apple Music sucked when it came out (the UI!)
- Spotify is more diverse with a lot of K-Pop, Video Game Soundtracks and Indie Artists
- I have my playlists there that took hours of work and I am not going to do this again on Apple Music.
So please let's just not get down the "Apple Music is better anyways, lol"-road here, shall we?