I hear ya...I was just answering the question as it was asked. I use file in many, many dishes besides gumbo. I guess it's a Creole thing...(and its reputation as a mild hallucinogenic).
I think Creole-style gumbo doesn't need any file because it's supposed to already be thick; however, from my experience cajun-style gumbo goes better with File because it's a bit thinner.