From Good to Great #3

It was a strange read this past week... The largest point of the chapter focused on the "hedgehog concept". Briefly put, it is the idea that a company can only do great if it does one thing amazingly and not couple things well. As a concept, I can see and agree with it perfectly fine. It makes sense. If I am a prodigy in math, shouldn't I just turn away from all the humanities and focus only on math? The problem I had with this theory/ concept was that the analogy also accidentally backfired. Even if I was a math prodigy, my GPA, SAT scores, resume etc. are all impacted by the other things: Language, History, English etc. So although I am focusing on math, my success is also correlated with the other things I do. The whole reading seemed like more of an idealistic way of thinking. Even our storefront project, where we have video games and computers, needs other things we aren't entirely passionate about (ie. chips, cards, drinks) but we still need it to succeed.
The reading so far makes me wonder if the "good to great" concept is merely just a very idealistic way of looking into things, or rather unrealistic? So far when I use the book's needs for success and apply it to the business'es I know and the storefront project, it is all very unrealistic in terms of trying to reach that standard the book gives us for greatness.