Prophets and apostles have expoused many theories. I think they're humans just like the rest of us. Unfortunately, these ponderings are often accepted as doctrine, even if it is not spoken as such.
My take has been (as an active LDS member) that Prophets are spiritual leaders, but most of what they say and do is not directly driven by God. Mormon culture (not doctrine) has cultivated this idea that anything/everything a prophet says is straight from God. If Prophets are infallible, and they are merely God's mouthpiece, what's the point in that? Why not just run the show yourself?