I saw the negative effects of smartphone access firsthand all around me when I was in middle school and the iPhone 3G had come out. Kids became antisocial. And this predates all those online influencers. The popular social media at the time, Facebook, was only about connecting with people you know. It was much more innocent back then, and even then it was a real problem.

More importantly, I don't see why a young kid needs a mini computer at all times. Same reason I wasn't allowed a GameBoy as a kid.

I was antisocial in school. It was before phones, and I spent recess reading books. Good times!

I was antisocial then became relatively social just because everyone else became even more antisocial. It's like that Simpsons episode where everyone starts acting like Bart, and he realizes the problem with that.