[onion2k]

Chat works well for close friends, but now I'm middle-aged I have lots friends from school, previous jobs, etc that I still want to know and I'm interested in significant events in their lives (having kids, changing job, getting married, moving house, etc) but who I'd have nothing to say to on a regular basis. If I rely on anything that requires active participation that just means I won't talk to them. I want to passively read about their lives, and maybe comment if I feel like it. Most of the time I don't.

This is a problem that you don't really start to understand until you're getting on a bit. When you're young you usually have a close group of friends from school or college, and maybe a job or two, and your extended family, and that's pretty much it. Fast forward 25 years and there loads of people who you've met and consider people you'd like to keep in touch with but who aren't friendly enough to want in a chat app. Social networks fill that gap really neatly.