On this note, I lost contact with a huge number of friends when I deleted my facebook ~15 years ago. Similar for livejournal. I handed out my email address and phone number before I walked away, but people have not used those to contact me at all.

I think people don't want to put any effort into socialisation. Getting a "feed" is so easy, it feels like you're connecting with people. You see the comments and likes. But everyone is lonely because they're not actively interacting, just passively consuming.