I guess we could note two things. First, the author seems to come from a place of success with their own personal story, so they're likely to believe in the system or thinking that they find brought them there. Lots of books are made in that way, and entire businesses are established like that, but whether or not it's going to be generally effective, or even just convincingly valuable to anyone else, is an open question. Second, if something hasn't been made part of a scientific consensus, chances are that the claims simply aren't good enough, or that the claims haven't even been submitted for any kind of approval anywhere. This is a way to both present a system or line of thinking as "novel" or "unique", and at the same time avoid potentially bad press from actually coming under scrutiny. - The Valsalva stuff has certainly been around for a while, but in terms of efficacy, I don't know if anyone's tracking how it actually performs long-term (which is indeed the pertinent measure in our case). In terms of the commercial domain, companies will typically only show positive stories, and neglect mentioning the negative ones (if they're at all geared for paying attention to those, which they probably aren't). So, I guess in short: Probably don't spend any money there, if you need it somewhere else.