Very interesting comment Callisa. I never thought of that aspect of overfilling. So you are saying it will suck the oil out of the engine and cause oil starvation? Not to mention the sliding wheels on the oil slick!
Another thought springs from your comment. Is it possible to have an over filled crankcase somehow get sucked into the blowby, then around to the intake, and hydrolock a cylinder or two? Pretty ugly scenario also, eh?
But I think this would not happen in a gasoline engine as the blowby (or PCV) hooks to the top of the valve cover. Diesels must have it mounted much lower?