Where to start. How about the idea that the phone is the tool or channel that has an appeal for behaviors that are addictive, rather than the cause itself. It can be loneliness, habit, peers doing it, it can be escape, there are a zillion thing "the phone" does. And yes, SV has learned to exploit the attention triggers. Saying it's phone addiction, while true, simplifies the problem with the description.
When I was growing up, before computers were in your pocket, the computers were big and under the desk. The big and under your desk computers had connections to BBSes via a modem and a landline, and later, the Internet. It's the same thing, except the big computer doesn't fit under the pillow at the bedstand. There was addiction to that in a similar way and for similar reasons.
It's a social tool being exploited. There were people addicted to the landline phone and talking for hours every day, it was just nothing remotely as harmful by comparison to craning your neck down as you look at some attractive person's video in their bathing suit from their palace in the Caribbean and feel envy and hollow when comparing your circumstance.