So, the fact that Wilwood sells thousands of drilled rotors that don't crack or fail means what? Pure luck? Or, maybe there are actually engineering solutions to dealing with stress risers.
How about the fact that airplanes are held together with rivets? Every single one of those rivets goes through a hole. Stress risers? Sure. But if every drilled hole inherently caused a crack in the base material we couldn't hold anything together with bolts or rivets.
