Especially considering that it's common knowledge in motorsports (although evidently less common than it should be) that more power only increases acceleration performance, but lighter weight increases performance of acceleration, braking, cornering, and tyre wear! Plus, reducing weight is compounding; take out one chunk of mass, and other components can also be made lighter, e.g., reduce the body mass, and you can fit lighter suspension components, brakes, wheels, tires, etc., and the light-weighting compounds.