I don't use too much, and I disagree somewhat about the only movement of oil on guns being due to gravity. Some oils, like Kroil, can creep upwards, especially if there is any opportunity for capillary action. When a gun's barrels are wiped down, then the forend is snapped into place, there is wood to metal contact. You also can't wipe down all of the rear of the action/frame without getting some on the wood. I agree that many people use way too much.
I don't see the big deal, really. it's just as easy to stand them muzzles down as it is muzzles up.
