Chronic fatigue syndrome, which affects one in 250 Britons, may be caused by a faulty immune system attacking the body.That is the problem with the "autoimmune" label: People think "well, if the immune system attacks its own body, then the cause must be a faulty immune system". No. Coeliac is an "autoimmune" disease, yet its cause is gluten (which is found ceral-grains).
That is one part of the problem with journalism: They try to explain things they don't understand. The other part is that people take what is reported in the press at faith value.
And, oh, by the way, the incidence for ME/CFS is closer to one in 200, if not more common. Doctors do underreport, it comes with the territory.