[jstummbillig]

Thinking as a fellow notification disabler, and having no data, just intuition: People want their attention to be tapped. I am not exactly sure why that is (although I am sure that it can't be good) but notifications are a tap on peoples attention.

Building certain apps without notifications seems like it would simply not be acceptable to must users. Most phone apps still vibrate or ring – that's basically a notification. I would go as far as saying its uniquely distracting notification is the primary feature of the phone app but, at the very least, a phone without one would be something very different. And since messengers basically compete with phone apps now, for most people that would probably not work.