well you see in theory all true sportscars should be made as light as possible. The more unecessary weight the more diluted the car becomes.
If you have a pile of interior parts made of OEM plastic and a pile of parts made of CF well obviously you can tell which will be less weight to lug around.
Every little bit counts. That's why Pedals are drilled, wheels are hollow spoked, Aluminum is used for doors now, 15 pound Braille battery vs. 50 pound OEM battery, lighter seats (like mine, way lighter than stock), lighter exhaust & headers. It all can reduce the onboard weight to that of having another occupant in the passenger seat. Otherwise you might as well be driving a porky 911
The object is to save a little bit of weight on every part all over the car. Even the gas pump will thank you. I knew a guy who was able to drop 500 pounds from a Miata! (he had a cf hood).