The idea that human personalities and behaviors can be sorted into two simplistic piles or even a scale between two piles is just silly.
There's no predictive value to it- you can't objectively classify\quantify people's 'vertion' and then predict behaviors or outcomes based on those classifications, not even statistically from a large sample set because it's meaninglessly subjective.
People are complex. Someone might appear 'introverted' in a social situation they're unfamiliar with, but in a different setting my appear 'extroverted' because they're very comfortable.
And some will say "social interactions give energy to extro and take it from intro" but what the hell does 'energy' mean in that context anyway? If I go to a small party with close friends all talking about sci-fi I'll enjoy myself all night and feel refreshed, but I'd be exhausted after 30 minutes at a rave and need a week to recover.
And do people migrate between intro-extro throughout their life? In my 20's I felt compelled to meet and experience new people all the time but now in my mid-40's I don't really care and tend to stick to the people I know. Does that mean I turned more introverted at some point? That's why even as a personality scale it's nonsense.
It's all just Myers-Briggs for dummies, which is already for dummies.
The only way it makes sense is as a description of immediate behavior, not of a personality. Someone may be 'behaving in an introverted way' but saying that makes them an 'introvert' is nonsense because they may go somewhere else and behave in an extroverted way an hour later.
I don't think they're meant to describe someone's "everywhere all the time" personality. I've met and know several people that fit into one or the other.
One friend is completely "alive" at D&D, but quiet and reserved at any other social function, whereas another loves going to concerts, parties, and other social events, but falls asleep trying to play board games.
I don't think it's meant to be an end-all, be-all. Just one way to generally categorize personality.
As far as people being complex? Above a certain level, yeah, definitely. But we also have a lot of very low level behavior that's relatively easy to categorize.
That's more or less how I think about it, except I'd rather use phrase it as 'categorize behavior' to emphasize the point that it's not everywhere all the time. People tend to think of personality as a more fixed attribute but we understand that behaviors can change in the wind.
Do you think it's nonsense in pop psychology, professional psychology, or both?
I wouldn't be too surprised to learn the terms had applicable meaning in some clinical settings, though I'd guess that was a world away from anything anyone that personally identifies as introvert or extrovert thinks of the concept. But I'd also guess that they'd agree somewhat with my distinction that that it's better described as a behavior than a personality- though they'll probably have more precise terms to apply to that description.
Ohhh, I think I getchu. It seems to be more of a problem for you in the use of "personality" non clinically?