I agree that the sports industry is trying to sell tons of unnecessary stuff. But only because there is not (yet) any scientific evidence doesn't mean that something doesn't work.

Sports academia has a long history of false findings and changing its mind. Just look at how the opinion about stretching changed, which in my humble opinion should be rather easy to assess.

Given this uncertainty I'd look both at academia and at what top athletes do. Keeping in mind that the top athletes have very different circumstances and needs compared to amateurs.