Because apple only maintains phones on an individual level?
And probably literally everyone who writes apps for iOS, as they would now need to account for everyone’s potential behavior.
It’s not “only”. Especially if you had to account for every possible variation in hardware. It’s more complexity and that means more opportunity for bugs.
They’re supposed to.
It’s all part of the service, right? Also losing internet could be dangerous in the same way a landline phone cable is. (Ie preventing someone with VOIP phone service from calling for help.)
It can also cause harm for people who work from home, etc.