Go to a racetrack with a professional racing driver. Give him a Toyota sedan and you get in a Porsche. Chances are, he'd still beat you. However, when YOU drive both cars, chances are you'll be quicker in the Porsche. Does this mean the Toyota is a bad car? Absolutely not. Whether the Porsche is worth the price premium only the buyer can say, because we all value performance differently.
And most of us can't afford a Porsche, but we still manage to get to work on time........
Not a fan of this analogy. I think there are some Canon lenses that are as you describe but there are other cases where Sigma and possibly others offer lenses that are better than Canon or have features that Canon does not offer.
I will agree that purchasing the best leans for a job is the way to go, but that lens is not always made by Canon.