This doesn't make sense to me. I'm definitely an introvert: shy, lousy at casual conversation, and can happily go for days without talking to anyone. However, I have no problem in my software development job with teamwork, communication or leadership (I was even a manager for many years before deciding to go back to being a senior developer). I can work effectively with others to get things done, taking the initiative when necessary. And, as someone else pointed out, I've seen many extroverts who have poor skills in these areas.