And once Spotify proves that then maybe we can have a discussion. There is no data to support that claim. I can think of a number of reasons why they weren't ready to provide audio API's like battery reasons. Also Apple has released audio API's both before Apple Music (iPhone) and after (Watch). Spotify is just mad they didn't get them sooner.
NO ONE is willing to give Apple the benefit of doubt, after they have unilaterally, retroactively mucked with app store rules to kill competition. The most egrageous case was with Steam, whose game streaming app was found to be non compliant after apple retroactively applied change of policy.