> It’s seems like this is kind of related to where bikers (cyclists) pay double for a component to save 100 grams instead of losing a bit of body weight.
Is kind of dumb argument. There is no tradeoff between the two. You can do both of these or neither. The additional weight in equipment will be there regardless of what happens to your bodyweight.
Perhaps they are hiking for extended distances without water where no matter how much you chug, it won't be enough?