While I agree with many of these takes, I believe there is more to this. For example, your point about defense from falling into panopticon by speaking publicly about things doesn’t actually require publicly speaking about anything other than politics. I mean, you can still hide all professional, creative or fun talk and still have the benefits you listed covered by only ever publicly talking about political issues. Another issue, is that publicity and interconnectedness of all discourses we have nowadays, increases a homogenuity of thinking patterns, in other words it hurts the diversity of the ways of thinking, that is also something that can be improved by more people going private and having closed interest groups in chats invisible to public web.
Everywhere? Every decade humankind becomes more uniform worldwide, but especially last few decades.
I feel like over the last two decades everyone on the internet was pushed to talk only in public, even more so, on the few biggest platforms only.