Over the past few years, I have been for real disappointed that Safari did not support: Vibration API, Push API, ResizeObserver, AudioWorklets, and on and on.
And then the product people say, quite reasonably, "Well, I guess we'll just need to build a native iOS app and pay the 'Apple tax'". Over which I don't think Apple are shedding many tears...
It's fine if they want don't want to implement everything.
The point is that if they don't get to simultaneously say:
1. The Web is a viable way to compete with native apps (which they explicitly said in defense in a current court case). 2. While not implementing features necessary to compete. 3. While not allowing anyone else to build a browser for iOS that implements the features necessary to compete.