Not necessarily. Look at how fast things changed for stomach ulcers. They were supposedly the archetypal stress caused psycho-somatic disorder. Well, that didn't last long once they realised they could cure it easily, quickly, and permanently with basic antibiotics.
Indeed. However, I have still encountered people, including doctors, who still blame ulcers in general (including peptic ulcers) on "stress". Apparently the science hasn't sunk in yet. The following sentence about peptic ulcers is a good example of what we may be hearing from the biopsychosocialists about ME/CFS if XMRV is demonstrated to be significant: "The prevailing concept of peptic ulcer etiology has swung over entirely in just a few years from the psychological to the infectious, yet the rich literature documenting an association between psychosocial factors and ulcer is not invalidated by the discovery of Helicobacter pylori.
" ( http://www.ncbi.nlm.nih.gov/pubmed/10633828
So there is psychosocial research which links ulcers to psychological stress. I have not hunted down these studies and looked into their methodology, but if the quality of "CFS" research is anything to go by, they certainly cannot be taken at face value and in some cases may be suspiciously biased.
But if such as association does exist, how relevant is it? Consider these statements: "Associations that have been found between acute or chronic stress and duodenal ulcer have been relatively weak, with odds ratios of 2 to 3." [...] "Personality studies have shown that ulcer patients are more neurotic than controls, but the difference is small and there is no evidence to indicate an ulcer personality.
" ( http://www.ncbi.nlm.nih.gov/pubmed/8505492
) I have come across CFS research which finds the same thing. However, notice how such findings are worded above as "weak" and "small", but when it comes to CFS the same association/strength is often grossly overstated.
Further consider the gist of this more recent abstract regarding stress and peptic ulcer, this may turn out true for XMRV and ME/CFS as well if stress is also significant. Basically, it may play more of a role for the minority (5-20%) of cases that test negative for the relevant virus, but the association is nonspecific and controversial. ( http://www.ncbi.nlm.nih.gov/pubmed/18537633