Correct. The experience that spawned this thread is only on Mac. If you look at the conversation history tab in SfB on Windows, you will see an entry for each separate session with a given contact. This is the SfB architecture. The Windows app is designed to put the contact list as the primary starting point, however, so most people are unaware of how conversation history is stored. On Mac, the Chats list (essentially, the conversation history) is a primary starting point for conversations.