I was answering in a neutral way, without particularly paying attention to who said what. It wasn't a life-or-death issue. Very simply, it's the same reason why racing car or sports car manufacturers sweat blood to remove a few grams of weight. When airborne, it's sweating blood to remove even a few milligrammes.
Once the weight is down, in a sports car, it is a question of the suspension, the steering, the engine, the tyres, and so on. In a fast jet, once the weight is down, again, similarly, it is a question of the wing architecture, the wing configuration, the engine and its power, and the combination of all these with each other.