She's absolutely right about that. However, although it's unfair and inaccurate we often judge the merit of an idea based on how well it's communicated.
Similarly, while there's no correlation between a person's intelligence and their ability to communicate, research has proven that we still make judgements on how smart someone is - based solely on how well they speak.
Many great ideas are never heard - especially in work environments that are often dominated by extroverts. Research suggests that a third to half of the population are introverted - if you would like to find out where you fall on the introvert-extrovert spectrum you can take a 10-question test on Susan Cain's new site Quiet Revolution. I took the test and it turns out that I'm an "Ambivert" - meaning I have both introvert and extrovert characteristics. Which explains why I thoroughly enjoyed delivering a workshop today and am now very happy to be alone in my hotel room thinking and writing!
The neuroscience-based approach that we teach in our workshops is incredibly helpful to those with introvert tendencies. We have developed a structure that ensures that every member of your audience receives exactly the right information at exactly the right time. Which means that when using this approach there is zero correlation between your level of introversion or extroversion and your ability to influence your audience.