It's a different kind of racing, some ovals you still have to break, and those high speeds are dangerous. Inside the car your adrenaline is pumping like crazy. Plus there's a huge difference in speed while you're drafting, so if you're leading you're a sitting duck. You have to drive carefully to preserve your tires, you have to mind your fuel, mind the engine, and your competitors all at the same time while you're going 200mph. Driving on a road course is similar but different, you're paying more attention to your driving, and again you have play the long game. When the speeds on road courses get too fast it's harder to have wheel to wheel racing. You have aero on the cars it's incredibly hard to follow because the leading car is taking away your cornering performance and the drag reduction doesn't compensate. Ovals kind of side step that bug-a-boo.