In fact, many schools are starting to ban phones on campus (for a variety of reasons, not just the negative aspects of social media), which makes this even easier.

Outside the classroom there are still plenty of in-person activities from informal gatherings, to sports teams, to clubs and civic events, and in those situations, the few people who are sitting on their phones are the ones more separated from the rest.

I think a lot of us who were early involved in building some of the web that led beyond Web 2.0 into algorithmically-driven media consumption see the massive dangers, and have probably sometimes even overreacted in terms of kids' access to it, but it's certainly better than the alternative.

I don't get how we got to the point where phones were allowed at school in the first place. Cell phones (though not smart phones) were around when I was a teenager and were universally banned in class and even in the hallways, except for emergencies. Even a non-smart phone is a huge distraction because of texting. Why were they unbanned?

Yeah and same with portable video game consoles, which of course smart phones are too.

Because helicopter parents that install surveillance apps on their child’s phone probably threw fits.

No probably about it. The schools are (were? I'm seeing a lot of school districts near me banning phones) trying to reduce friction with (troublesome) parents who demanded 24/7 direct communication and surveillance.

Your first sentence is true. The rest of it isn't remotely close to being true (starting in around 7th grade).

Your kid's school day changes to be much less after 7th grade? Which messaging app doesn't work from a computer?

I'm not speculating here, I am telling you how it works.

Phones ARE banned from school and the kids DO socialize in person there.

But then they all get home and stay in touch. Some have phones, some have tablets, some just their school-issued laptops. But they're constantly talking, 1:1, in various overlapping group chats. They organize getting together in the neighborhood or meeting up elsewhere over the weekend. It's where a lot of the drama happens (which isn't great.)

If you prevent your kid from accessing this communication layer, it will 100% affect their social life.