I look at it this way: Imagine a world where the concept of a telephone never existed. We all have these portable hand-held computers, but nobody's ever experienced a "phone" before. Now suddenly an app developer invents a way for "anyone in the world to anonymously contact your device, without your consent, have that device (by default) interrupt what it's doing, (by default) ring and/or buzz, (by default) pop up a full-screen modal over what you are doing, and if you press the button, that anonymous person is able to activate your device's speaker and microphone.

I don't think this intrusive app would pass either major store's guidelines. This kind of device takeover/intrusion would be totally unacceptable to many (most?) users.

But, since we already have a concept of what a "phone" is and have gotten used to it, culturally we let it slide.