Narcissistic Supply, the problem with the word "cult" is that it's definition is kind of vague. From a dictionary standpoint, it is defined as a usually small group formed around a charismatic leader. I believe "closed-society" is a word that better fits the JWs. The problem is that "cult" has a well-known negative meaning which makes it easier to convey the negative impact the JWs have and "closed-society" sounds benign until you understand that the term basically refers to an authoritarian belief system where it's adherents blindly follow direction from a higher authority (sound like the GB)? It's all about unquestioning obedience.
So the reason I say they aren't a cult is technical. They have all the characteristics except for a single charismatic leader and they aren't a small group. Yes I analyze things to death, forgive me.