The only addictive part, are the social interaction notification (you got mail, text, follower, comment, upvote) - or skinner-box game, but Candy-Crush is already classified as pure crack no?-
More precisely the addiction come from time delayed interaction. Phone call are not addictive. Neither are Chat room.
We are social creature, so we crave social approval. But only delayed one, and only when they are sprinkled in time, because, else, it is draining. So I guess we're just remotely social creature.