It depends really whether you as a kid can have a social life at all without being on social media. If your school is one of those no-digital-devices places where tech workers send their kids to, then you'll manage. But most schools aren't like that. Instead, there, children heavily rely on online services to communicate. I'm a late millenial, so I didn't have 100% the same experience as a kid growing up now has, but even for me, I felt it on my own skin. A lot of social interaction was inaccessible to me due to me not being on Facebook by choice. When some event was planned, I didn't immediately know about it.
Also there is the practicality point. In the old days, kids could reach each other from their own volition, back when kids walking on the sidewalk alone wasn't a reason to call CPS. Back when said side walks existed in the first place.
I was exaggerating a little, but the issue still exists. There has been a change in general societal mindset around deeming the outsides as dangerous for children, even during the day. This mindset might not exist everywhere, but where it is prevailing, it is forced onto parents who let their kids out in the sense that they are looked negatively upon.
I've lived in several places and never had this problem. My instinct is that this is just another moral panic - not any different than fearing of child abduction when letting your kid walk to school.
Also there is the practicality point. In the old days, kids could reach each other from their own volition, back when kids walking on the sidewalk alone wasn't a reason to call CPS. Back when said side walks existed in the first place.