They don't need to back it up. It is up to the person making the original claim to back it up.
There's half a century of research and practice into this topic. Anyone in the industry _should_ know about this. Anyone who doesn't can find it on a search engine within 30 seconds.
There's half a century of research and practice into this topic. Anyone in the industry _should_ know about this. Anyone who doesn't can find it on a search engine within 30 seconds.