In a C&V, present context, I think one should try not to over-think the elements of weight weenism and try to justify them to such extent that one starts not to enjoy a really lightweight bike because physics might instill doubts if any seconds are shaved off a race by it. Whether it's climbing or accelerating, I'm pretty sure a rider will feel some sort of change, most likely for the better when riding or even just carrying their bike up some stairs...... Just do it if you can and have lots of fun doing so!
For me personally, I see light weight with a bike as something like displacement on a car..... you just can't have enough of it if you want maximum fun!...