There is privacy on the Internet. I think it is an illusion that you cannot have privacy on the Internet.
Sure, Person A can always DECIDE to talk to Person B. But that does not mean I voluntarily tell Person B everything that I only want Person A to know. This specific argument of yours doesn't even have much to do with the Internet.
You are basically saying it is useless to ever share anything with only a specific group of people because the specific group of people can always just talk to everyone else you don't wish to share the information with.
Sure, Person A can always DECIDE to talk to Person B. But that does not mean I voluntarily tell Person B everything that I only want Person A to know. This specific argument of yours doesn't even have much to do with the Internet.
You are basically saying it is useless to ever share anything with only a specific group of people because the specific group of people can always just talk to everyone else you don't wish to share the information with.