one of the reasons that many doctors are suspicious of this condition
I also think that far too often people presenting with chronic tiredness, or general fatigue, get told it might be CFS. They probably latch onto that far too readily. Most cases will be misdiagnoses. I think scepticism is understandable most of the time because doctors are well aware of regular post viral fatigue and that it typically resolves itself over some months. I also think that too many think ME is CFS and these are both prolonged chronic fatigue. Now who has what is not the main point here, its about diagnostic criteria. Few doctors look up and use them, and there are many poor criteria out there.
Most doctors are also unaware there are many tests that can be done, and five from 1954 or prior. These are not diagnostic (with caveats, some might be validated as diagnostic in time) but establish what is physically wrong to a large extent. To be fair one of those tests was probably not clinically viable till the 80s or so, and the another was only validated for ME/CFS 10 years ago. In fact the first was not validated till 1995, nobody bothered to do that. Yet these kinds of tests were sometimes used by doctors in the 80s at least, and established some kind of pathophysiology.
Those tests are the tilt table test, quantitative EEG, mass spectrometry, CPET and a sleep study. Of these only the sleep study is probably commonly used by doctors looking at fatigue states or related symptoms. Mass spec is still not clinically viable as its uncommon to find the equipment except at research hospitals from what I can tell. qEEG is commonly used for stroke patients, CPET for a variety of conditions and for athletes, and the TTT is specific for orthostatic intolerance. There are lots of more recent tests too.
I look to the history of other diseases for how and when attitudes change. Diagnostic testing is critical, but someone recently mentioned that treatments count too ... once reliable treatments are available most doctors want to use them, though the take up time can be one to two decades. This happened with MS and gastric ulcers.
Attitudes change when there are tests and treatments. Multiple tests are being investigated right now. Treatments are mostly still experimental or hypothetical at this point. No treatment that works has been approved via the appropriate medical processes, which would include the FDA in the US, and phase 3 clinical trials more generally .. yet.