And you know this how?

I just think for someone to choose directing as a career must have interest in film?

well it's a realistic point to bring up. I mean, when I think film buff is someone who just spews out all this film talk with strengthen knowledge on the topic. Just cuz you work in it doesn't mean you know heavily detailed material on previous works.

Obviously they may have an interest in film, but like in all careers, people may do something for a living, but not care enough to know the history. Just like in sports how there are players who trully appreciate/care about the "history of the game" versus other players who may be great or even better that just care about playing the game and have since they were young. Sure they may have had favorite players growing up, but they cannot rattle off ty cobb's career stats or something like that.

I think the Coen brothers should be added as film buffs, if not already mentioend (did not comb through the thread again). For an example of a director I think has no sense of film history...Brett Ratner. Sure he knows and famously wrote a letter to $peilberg, but I think that is about it.

As for Kevin Smith, I think he is far more a comic movie/pop culture buff than a dedicated film buff. I cannot imagine listening to Smith lace a conversation with obscure foreign film references or even silent cinema (other than say, Chaplin or Keaton) or old studio Hollywood references. He always struck me as a pop culture/comic guru that writes great dialogue and will occassionaly cite films that most comic buffs would know (LOTR or Star Wars). Not sure he is one to "steal shots" like Tarantino or Scorsese.