A company not providing you and API you want does not equate to them blocking you. FULL STOP.
Spotify had some decent arguments (re: 30%, IAP, payment) but it fell 100% flat when they started giving equal importance to things that were not targeted at them. The lack of music API's on homepod, watch, iPhone are not some direct slight against Spotify and to pretend they are only shows Spotify's inflated view of themselves. Put simply: NOT EVERYTHING IS ABOUT YOU.
Spotify is twisting the truth to it's breaking point in this post with just enough truth sprinkled around that you might not notice the bullshit.
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.