35 years of working on Highways, the post is factual, The sand and oil lets loose “wear” making the road rough and the bigger aggregate stick up. When you seal coat a road, the rock is only there so can drive on the road, It’s the oil that seals the surface. If this was not the case you would never have to seal a road .. Far as driveways, if it’s smooth it’s really not necessary to seal. If this wasn’t the case blacktop would last forever. Fill the cracks. DK.