Very good rebuttal. I'd add to it that there seem to be two main misconceptions at play here too:

No matter who you are, you still need other human beings to get motivated

What does it really mean to be introverted? If your introvert/extrovert classification is lynch-pinning on motivation, how does that apply to individuals that just aren't very motivated to begin with?

More importantly though, introversion/extroversion is most likely a gradient (kind of like gender). Most people don't 100% fit in a nice pigeonhole of a label, but for succinct communications labels are very useful and efficient. That is to say, a 60/40 and 90/10 (introvert/extrovert respectively) are both "introverts" but would most likely have observable differences in social behavior. In fact, the spectrum itself is basically describing behavior.

Though, to that end of behavioral assessment there is definitely some re-evaluation needed for our criteria of what is a "genuine" social encounter.