What has changed is Apple has a direct competitor product. Firstly, that competitor product has technical advantages as it can access APIs that Spotify cannot

What has changed is Apple has a direct competitor product. Firstly, that competitor product has technical advantages as it can access APIs that Spotify cannot (SiriKit, background audio on earlier versions of WatchOS). Secondly, that competitor product is at a financial advantage because of the 30% fee. It's not the fee itself that's the issue. It's that Apple is (arguably) using it's control of the platform to compete unfairly against Spotify.