My view on 2 is that you get into a quite different mindset when you program actors, compared to objects. For starters, since each actor is scheduled separately, it becomes routine to not assume too much about the internal state of the actor. So you won't see many getters + setters in Erlang, for example. You also need to structure your program to not communicate unnecessarily, since communication may fail and requires you to wait for the other actor to reply. This makes you to think about what state should belong to which actor. It is quite subtle and is best seen by experiencing it, but I think the programs turn out quite different, and in my view better. Actors are not perfect for everything but to me they are what object oriented programming should have been.