One issue I encountered today with my Mac is that I had to log out of a user who was logged into my Mac and I didn't feel like going to his session (with consequent music and workflow cut-off) to do it.
It is something that is not as easy to do as in Windows, or at least I have not discovered this simple way. What I have been able to verify is that if you close the "loginwindow" process corresponding to the target user, you already have it.
It is not as aesthetic or logical as other system functions, but it works.
Sure it works? I have verified that after closing the loginwindow process of another user, the user does not seem active, but still has many other processes open.