[Inky]

This is possibly another of those "what would a world where these spells were common look like?" questions. If the 3e version - anything caused by micro-organisms - was widely available, that might have got germ theory off the ground much earlier, as healers catalogued the large category of "conditions that Cure Disease works on", and started to wonder what the common feature was. On the other hand, it might have held it up, if they got the idea that the spell worked because those conditions were magic-based.

If the 4e version worked on scurvy, on the other hand, Cure Disease would become part of the list of spells every ship's wizard needs to know, and long-distance sea voyages would suddenly be a lot easier (apparently scurvy was one of the big limiting factors during the Age of Sail).

(Incidentally, since the main mechanism of scurvy seems to be that tissues don't heal and gradually wear out, would Minor Healing (much lower prerequisite count) temporarily fix the damage if you didn't have Cure Disease? Which might mean that if you were showing scurvy in your game for some reason, an appropriate mechanism might be temporary Unhealing... sounds like one for "horror at sea" games only.)

If you said that Cure Disease couldn't cure "chronic conditions" permanently, there might be a difficulty defining "chronic condition". In the 19th century, type 1 diabetes and tuberculosis were both slow-burning terminal illnesses. Now one is a chronic condition and the other can be cured permanently by antibiotics. If it's defined by what's a chronic condition in the TL the game is set in, then it seems like you get that awkward thing of it being dependent on how intractable the wizard thinks it is, or on how intractable it is by non-magical methods that might be unrelated to what the wizard is doing. But the Healing advantage already seems to use that system, so possibly it works, even if the illogicality of it might annoy some players!