This is clearly written by an adult who forgot how most children behave. If they're the only ones without a smartphone, they'll be single out. Especially with how prevalent online communication has become. They might not be bullied (though they probably will be), but growing up as the outsider comes with is own can of worms. They'll most likely survive it, but it'll have it's effect... But everything has consequences…
Even if they AREN'T bullied for lack, they'll miss out on all the socialization. When I was a teen people talked on the phone, they hung out at the mall. I barely did. When not at school, I stayed at home to care for my younger brother and make sure dinner was made (child of a working single mom). I went out of state to my dad's place every summer, so I never spent summer vacation around my school peers.
Now I'm an adult, and I don't have close friends. I never have. I don't know how to open up to people, or how to hang out with people where it isn't an obligation on one part or the other. I remain aloof, then desperately overshare (case in point), then feel awkward and embarrassed and withdraw. I've had two serious relationships in my life...and got married both times.
Today's kids won't be talking on the phone, they won't be texting, they won't even be tweeting, they'll be snapping or instagramming or any number of things. They'll be sharing the experiences they have in common and generating those experiences, and for many, MANY of them those experiences will be around smartphone tech.
And this author has decided their kids don't need that shared experience. That comes at a cost.