"Put down that wrench!"

Interesting question. Historical precedent, I'd say; SF fandom has a very early claim on the term (although the OED notes 1928 for baseball fandom, and US sources place it around the turn of the century). The jargon of HP fandom is very close to that of SF fandom (fanzines, fanfic and so on), as one would expect from what is effectively an offshoot of SF fandom. What surprises me is that HP fandom has comparatively little awareness of and overlap with mainstream SF fandom.

Bah. Maybe I'm just an vile elitist written-SF fan.