[elcomet]

Public / private and walled garden are not what you are saying.

I'm saying only your friends on Facebook will see your posts, so it is private, unlike twitter where the whole world will see them. And you can create groups if you want to have even more private discussions.

Twitter, LinkedIn are walled gardens, but public ones. Facebook is a private walled garden.

[johannes1234321]

Yes, but "friend" has quite a wide meaning on Facebook.

Compare it to a WhatsApp group: there one defines exactly the people who should see a given message. "Friends" becomes mixed between "true" friends, neighbors, colleagues, ... people you once we're closer with but passed ways to some degree, ... after a while it's semi-public at least unless you have a strict (un-)friending policy. For average users the visibility is also hard to understand.