The simple point is that you cannot 'learn from clinical experience' unless you make controlled observations and in clinical practice you don't do that most of the time.
I'll be blunt now. It seems like you are making a lot of assumptions without actually knowing or even bothering to try and look things up. A quick Google search will show you that Rowe has published research articles on this since 1995 (maybe even longer?), so it's simply not true to suggest that he never makes controlled observations. I think you are being unfairly dismissive and judgmental about him and his work, and the actual impact it has had on the POTS/dysautonomia field and pwPOTS/dysautonomia over the years.
At least these people seem to be genuinely trying to help and learn more, through research and roundtable meetings and more. To me, that's worth something. It's not enough, but it's a start.
Do remember that POTS and dysautonomia as labels can be meaningful also in other than evidence-based ways, to many of us. For example, using the labels to find others suffering from the same symptoms has been very helpful for me, and has allowed me to learn so much from other people's experiences and the advice they have gotten from the specialists they have seen over the years. I've learnt a lot that has actually helped me in very practical ways, had an actual impact on my life and my functional ability.
Just like ME, POTS and other kinds of dysautonomia might not be perfect labels or well-defined diseases, but it's very apparent when you talk to others suffering from POTS and other kinds of dysautonomia that it isn't a random heap of myths and made-up stuff. Just like a pwME can recognize another pwME, the same is equally true for pwDysautonomia.
We definitely need more research, urgently. But in the meantime we're all just literally trying to survive, to get through one day at a time, sometimes even one moment at a time. And from this perspective every little bit helps, even imperfect offerings such as those from Rowe and others.
Just because you
@Jonathan Edwards don't see the value in this doesn't mean that it's worthless nonsense.
(Edited spelling.)