I've always felt that the introvert/extrovert dichotomy is such an oversimplification that it fails to be useful as a form of categorization. The degree to which someone is outgoing vs reserved is highly context dependent: maybe an individual is extraverted in their personal life but more restrained in a professional environment. Measuring these things is also so subjective that much of this is just a wash. Pieces of business-pop psychology like this one seem mostly designed to tell their audience wants to hear with just enough of an edge to provoke engagement.