Yes and by no means am I stating that we take all traditions or techniques for granted; otherwise we'd still be sticking leeches on people. The point is that in n=1 studies (ie. self experimentation) one can learn a lot more and a lot faster than by waiting for a double-blind study to be conducted on the subject matter.

The same is true in strength training, where coaches like Charles Poliquin used techniques that weren't "scientifically validated" till decades later.

Meditation and mindfulness has pre-dated Calm, Headspace and the SV bubble by a couple of millennia so it's important to have an open mind to practices that don't yet have papers in PubMed. Just because a doctor can't prescribe it to you doesn't make it bogus.