My son is 10yo, we want to give him a phone when he reaches 12. It's becoming a bit more difficult, a lot of friends already have one so he keeps asking but he just has to wait :)

I'm not to worried about social isolation. This will vary from person to person. The article mentions all the fun things the writer did when she was a teenager. However, when I was young some kids were addicted to gaming on there 486 or 8bit NES, never met any friends. The tone of the article is a bit 'in the old days everything was better'

Not having a phone will cause some isolation as well. A lot of meetups with friends are announced on app-groups. That was actually the moment when I decided to buy a smartphone myself, when I started missing out on parties.