I guess the National Cancer Institute, Mayo Clinic, IARC (2), National Institute of Health, and the American Cancer Society are all wrong then? You should be careful using just one source of information, especially when there's a clear confirmation bias.
Also, it is 100% proven. The site you list admits that the risks are already proven. They're just trying to downplay the risks. Many of the "sources" that the site lists have clearly biased language in the titles, leading to skepticism of their validity.