> Even with "circles", if the people in group B know you by the same name as the people in group A (say, work), you have no privacy at all
The communities that you mention exist IRL; do people use pseudonyms in real life in an attempt to protect their privacy? In my experience people nearly always go by their real name, even when they are doing things that they really wouldn't want their workplace to know about.
Why would someone contact your work to tell them that you were part of an unusual community? What would your work even say if a random person came and told them that? What you are describing sounds like it only applies if you are doing something so extreme and socially unacceptable that a random stranger who sees them on the street would think "I need to make sure this person doesn't get away with doing this".
The communities that you mention exist IRL; do people use pseudonyms in real life in an attempt to protect their privacy? In my experience people nearly always go by their real name, even when they are doing things that they really wouldn't want their workplace to know about.
Why would someone contact your work to tell them that you were part of an unusual community? What would your work even say if a random person came and told them that? What you are describing sounds like it only applies if you are doing something so extreme and socially unacceptable that a random stranger who sees them on the street would think "I need to make sure this person doesn't get away with doing this".