Twenty years of psychiatric dominance over the condition, the view that it's a behavioural disorder and the simple fact that young medics get little or no training in CFS/me at all. And there is still a hardcore of GPs and other medics who simply don't believe it is an illness at all.

You are certainly correct that ME/CFS is a "medically unexplained syndrome" - that is we do not have an explanation of the mechanism that underpins the collection of symptoms that we recognise as constituting the syndrome. However, nobody treating CFS /ME in the NHS believes "it is a...