Since there's no one here opposing that, I'm pretty sure that's not your issue. See below. Did you know there are no U.S. medically approved studies that show marijuana works? Nevertheless, the people that use it and have been using it for years already know the answer that question. Similar with the aforementioned performance enhancing drugs. Where's that documentation? Still, you'd have to be deaf, dumb, and blind to deny their effectiveness.
The scientific method is great, nobody's disputing that, but when it comes to health and fitness not everything supported by a trial is foolproof. Despite millions of dollars spent and decades of analysis and testing results there are still people that are resistant to certain
FDA approved drugs, and sometimes the cure can be worse than the disease.
In the end, people believe what they want to hear, and will always find a way to ignore, deny or go against what they don't like and choose not to accept.
And he said unto him, If they hear not Moses and the prophets, neither will they be persuaded, though one rose from the dead.