And I am free to use Google Music, Apple Music, YouTube Music, Deezer and even Tidal. Nobody is forcing me to use Spotify.

But, if I have an iPhone, the only application store I can use is controlled by Apple.

In other words: if I am an artist and I want to offer my music via streaming I have plenty of options. If one of them does have a deal that I find unfair, I can choose others.

If I am a developer and I want to offer my app to iPhone users, I have only one option. And if I am banned from this store for any policy infringement (which sometimes is ridiculous and totally arbitrary) I have no other option to offer my app to iPhone users.