Benefits: For the man, the feeling (with some lubrication) is surprisingly similar and the eye-candy of having sex in doggy style is almost identical. The benefit to the woman is that she can please her horny boyfriend with the moral overhead of a hand job and not have to "go all the way".
This position has also been referred to as Doggy with a Dike. This author is not sure why but presumably originating from a creative lesbian meeting some man's advances half-way.
Bro: So you just got a hand job then. Whatever
Dude: Try it sometime. I was hittin' that shit like crazy. Couldn't even tell the diff.
Bro: Thats okay, I don't go to Bible study classes to pick up girls.