[bartc]

I think it's because friendship-level connections are a lot easier to make when you are in uncomfortably close physical proximity with each other and/or when you need to rely on others and they need to rely on you.

In upper middle class society, more and more people live alone and have access to everything they need without needing to rely on neighbors.

Having 24/7 access to the Internet and communication tools gives the sensation that you have all the necessary tools at your disposal, but in reality those tools do nothing and you're just sitting at home by yourself, ignoring the people who are physically around you.