I suspect they see it more like hysteria or neurosis than MS or RA. With "secondary gains" thrown in to blame us for wanting to be sick. They've reduced the cure for ME to being a mere matter of willpower on the part of the patients. Changing our thoughts is therefore always considered curative, ergo failure to be cured is a failure to want to be cured. I doubt there's a mental block. It's deliberate propaganda, which benefits the BPS proponents by building their careers, and the politicians by being able to claim a "scientific" excuse for cutting expenditures on our health.