you can have a smartphone (I don't) and be very miserable and lonely (i’m not). I bet that's even the daily experience of a lot teenagers.
A smartphone may help to get in contact with people, but it's not a necessity by a far stretch.
Again: a (sometimes painful) emotional and social education is what teenagers need. Soft skills are hard to learn.
Group chats on Facebook / WhatsApp / Telegram are how people share experiences, learn, set up meetings or parties. All the people which I've met so far who didn't use those platforms were socially isolated. Not sure whether it's correlation or causation, it still does count.
Obviously, having a smartphone won't magically bring you friends.
> Obviously, having a smartphone won't magically bring you friends.
No it won't - it's not necessarily social death to avoid these platforms, but it was an intense struggle to grow any friendship without it. You need to go where the people are talking to each other, even if you dislike where they're standing.