I think what Dek is trying to say is this- if you only like the song "Yellow Submarine", but hate all other Beatles songs, you are a Yellow Submarine enthusiast. You are not a Beatles enthusiast.
What makes me crazy is when people abuse me because I like things that they don't. The same guy that Dek is talking about basically called me a moron because I like DisneyWorld. I really like DisneyWorld, so that offended me. :-)