Yes, those things certainly do happen. And do you think Mr. Armstrong gets back on the crashed bike the next day? My guess is no. Of course bikes are built to withstand the elements of the road. Intentionally putting unnecessary stress on a frame is just well, stupid. When you ride do you not lift your ass up off the seat when you hit a pothole? Do you not swerve out of the way of a big sewer grate? Do you attempt to lighten the load when rolling of train tracks or whatever? I know I do. Those would obviously be stressful to the frames integrity and the wheels had you just kept your fat ass on the seat. Sure it can withstand it, but what is the point in potentially damaging it? What is the point of putting undo stress on your frame whether it is from bunnyhopping or riding "heavy" on abused roadways? Take your own advice and take care of your ****. Stress is stress, anyway you slice it. I chose to avoid it if I have the option. I would suspect builders assume their customers would want to take care of their frames as well.