Well, since I can't tap into the heads of everyone asking questions, I can't really answer this without completely making up some obscure theory.
But personally, I don't ask ANY questions to incite debate, although I think there's plenty of that in the forums.
I ask things that pop into my head, and they range from something that might be directly useful (gardening tips, or cooking ideas), to random musings about life (is there a such thing as "love at first sight")...
So, there seem to be two variables - 1) who asks these sorts of questions, and 2) who asks questions more often. I suppose I could probably come up with some algebraic formula to quantify this for you, but ultimately, that still wouldn't answer your question.