Introversion and extraversion are valid concepts in my opinion.
I find the most useful application of this is how to deal with ourselves and others in time of stress or duress.
When in need to 'recharge' the introvert will want to be left alone, to be with oneself. The extravert, on the other hand, will recharge his/her batteries by searching out for company and talking things through.
Also, I must say, that the article seems to imply that introversion has a bad rep and a negative perception but it doesn't have to.
Depends how you were taught. Some times you might need people to "recharge" for some situations. Others you might need to be alone.
It seems that everyone today is an introvert. For me it signals how nonsense the term is. It is some kind of "special budge".