the idea of a spectrum is still relatively new. Medicine goes through these fads all the time. There's also a natural tendency to define syndromes broader than they actually are. It still seems a very loose definition of the term, as they still, as far as I know, have yet to identify the underlying biological mechanism.

This is not to diminish anyone's suffering. There's also a danger of taking false refuge in a syndrome that can be equally demoralizing and even paralyzing. No one should be defined by their diseases or medical conditions.