Having people used to a certain concept and then migrating that concept to the web contributes a lot to the success of a product. It saves you the trouble of introducing abstract concepts to the average user, which could be sometimes troublesome.
However the generalization of this observation is incorrect, it is inaccurate and should not be used as a rule to define a good product and\or startup.
Dropbox: P.O. Box? You can send almost anything to it but only X people have access (whoever has a key)
GitHub: Science Publication? Where everything is typically based off prior research and people can choose to "Fork" previous research to publish a new concept
Klout: Diner's Club Card? Masons/Lyons clubs?
Bottlenose: TV Guide?
Just taking stabs... it is an interesting question but I agree I'm not sure what the benefits are for being able to relate directly to an "offline" concept.
I suppose one benefit is if you really can say "We are like TV Guide for the Internet" then you can use that to help you make decisions (what did TV Guide do right and wrong).