Good point. In my case, I had EBV early November 13 years ago. confirmed by lab. I felt horrible, unable to work, but mainly exhausted with liver pain. In 5 months I managed to fail 2 return to work attempts, was found to have a large ovarian cyst and got a necrotic gallbladder. It was a month later that i experienced my first orthostatic intolerance symptoms along with depth perception problems, heat light and sound sensitivity.I guess I would wonder "how long after an infection?"... like within a week? A month? I think some long covid cases have developed even later than that.
Also, "after an infection" could mean mean "after the initiation of an infection" or "after an infection has resolved."
Not trying to be picky. I think the infection requirement is probably a sensible way of trying narrow things down. Mixing infectious onset with, say, chemical exposure onset might confound things when so little is known about the mechanism of either.
You have to give someone a chance to recover from their initial infection before you can diagnose them with ME or even long-COVID, whatever that means to them (and i’d wager even doctors do not know what the long covid case definition is) ; chances are, they will.