You would only say this if you've never pushed a big heavy front engined car, and a lighter rear engined car (or for that matter, a mid engined car) through some curves at speed. Your grandmother could tell the difference between a Porsche and a Corvette. I agree that perhaps in normal urban driving you wouldn't notice the difference, but who buys those cars primarily for the drive to the supermarket? It's the same with bikes. I don't notice much difference between my tourer and my track bike or my tighter angled road bikes when I'm pootling along a boardwalk looking at the sea at 10 mph. However, when I'm diving in and out of urban traffic I sure can tell, and also when I reach the end of a 50 mile ride.