That GP should be reported. They're not following NICE guidelines for CFS, and they are failing their patients. It's easy to mock people with chronic fatigue and laugh about sending them away with a placebo, but that's abuse and should be stopped. That GP clearly doesn't want to treat them, which isn't fine but understandable. But that's why we now have primary mental health teams to refer people onto.
Fatigue is a non-specific symptom and is not necessarily chronic (fatigue is only classed as chronic after 4 months -- according to the article you linked).
Nobody was laughing about it or mocking: we were discussing medical ethics quite seriously, and the medical value of placebo.
As I understood, the GP only applied this to situations where by-the-book they would have to send people away unmedicated and dissatisfied.
Although you might reasonably disagree with their methods, the GP felt quite strongly about it: believing that showing care in such a simple, non-harmful way early led to fewer chronic cases.
"someone, somewhere at some time was pushing them as an amazing cure"
I've also heard a GP (who I personally respect) say they prescribe Vitamin D as a convenient placebo for common fatigue-type symptoms.