Earlier quoted context omitted.
I think we've become so addicted to smartphones because they are new and shiny, quite a leap from technology we knew over the last 20/30/40 years. Children born with smartphones around see them as ordinary and probably less addicting, it's what comes next we need to worry about for them.
Aanecdata I know, but I have a couple of young nieces (7 and 11) and they are definitely as addicted to smartphones (/iPad) as you can reasonably get. Edit: Observing their behaviour, and my own (and other adults), I'd speculate that they are inherently addictive rather than simply new and shiny (I don't view them that way any more). To be honest, I find this pretty self evident.
At one point, we paused the movie due to an ambulance outside, and the boy lept from the couch to his phone to get his little fix.