Lord of the memes

I think it's simply that these activities are more enjoyable with less weight. Hewhen hiking it matters a lot, carrying heavy load on your back sucks. In cycling people definitely obsess a bit too much because most people aren't competing, but climbing is definitely easier on a lightweight bike. And people are apparently willing to spend a lot of money on this stuff, so companies gladly make carbon everything to save 5% weight at 500% the price.