Because science insists that a finding be reproducible by anyone who is a peer to the scientist publishing the finding. It isn't science until someone approves of or agrees with or gets the same result as the person submitting the finding to scrutiny.
In my younger years, we heard claims like Laetrile kills cancer. It was such a wide spread popular belief that Sloan Kettering (one of the most famous of all cancer clinics in the world) decided to test it rigorously. They found nothing except a toxicity. (Laetrile is derived from peach pits and if taken orally will break down to cyanide which is a poison). If you are under 60, my guess is that you are going to have to do some research to find out what Laetrile is, what it does, what it doesn't do, and why you shouldn't use it. Thank goodness the fairy tale of its effectiveness died the death it deserved all because the claims were submitted to testing.
If Laetrile wasn't tested, and people relied as they always had on medical folk tales rather than the scientific method, many more people would have died than did.
