It's too bad that common sense just doesn't seem to be that common anymore. This makes sense - but their "predictor" statement is backwards.

In youth, being outgoing is a natural trait of children. Those who cannot keep up with their peers intellectually will not be able to express themselves, and end up resorting to anti-social behaviour (bullying - though kids see it as strength, any sane amount of investigation will see that it's just a front for weakness). Thus, those who can keep up (IQ's of 80+, give or take) will retain their openness for a bit longer.

But, after graduating (whether high school or post-secondary), the smarter ones will start teaching. Teaching their peers, their coworkers. And, eventually, they'll hit some brick walls, because they don't know how to teach. And they'll become bitter when people excersise their free will to oppose their "obviously" superior advice. They'll learn ('cuz they're quicker on the uptake) that people only ask their advice if they've already made up their mind to do something "obviously stupid" and just snap at others, not always being aware of the difference between honest questions (really wanting to know the answer/opinion) and sham questions (already know what they're going to do, just going through the motions of asking). And then the frustration at explaining things that are beyond the listener, and the listener not getting it...

Besides that, in knowledge fields, such as computing, companies don't hire people to be "yes-men" - we don't want to just hear "yes" to everything. We need people who can confidently disagree. Because that tells us they're paying attention, and that we aren't infinitely superior, but probably have missed something that another viewpoint can see.

I dunno ... I just think this is somewhat an obvious part of human nature. I'm not trying to justify it, just state it's common sense.