I was playing around with Activity Feeds today and I noticed that when you create a Post via workflow, the post will not be public for everyone to see. The user that wants to see posts for that record will have to either follow the record manually, or you can create a follow via workflow. This is very powerful because you will be able to create the post and create a follow for someone specific E.g. if a case is created, an automatic post and follow can be created for the user’s manager.
This allows for managers to only see posts that are relevant to their teams.
Hope it helps.