Many of them could, in fact, stop being vocal. They did not have an incentive to. They had an incentive to be/become vocal.

That's the fundamental issue which has very little to do with extraversion. The world rewards loudness, and most attempts at making the world slower and more silent are actively thwarted.

There are degrees of introversion/extroversion as well.

Of course there is no us and them

But them they do not think the same