I'm starting to doubt that you have ever met Introverts and Extroverts that you have understand them, part of the "problem" is that most people rank somewhere in the midle and you can't easily tell the difference in the first place. Another point of posible confusion is when an Extrovert or someone that "ranks" somewhere in the midle lives in an environment that forces him to behave more like an Introvert, ofcource he is not an Introvert! and you could be 100% accurate in this case, perhaps it's this group of people and behaviour that lead you to post this article.

"No, you are not an Extrovert" could as easily be as accurate as your title is.