"I could just as well say that extraversion goes along with overly assertive and aggressive behaviour and other behaviour that makes collaboration a nightmare"

I don't really see this very often. If someone isn't writing documentation or writing proper tickets, I don't think it has anything to do with being an extrovert/introvert.

"because everyone is different and you can't just generalise like that. Being an introvert doesn't mean you're bad at communication or avoid confrontation"

I've worked with lots of introverts over the years and although you may see it as a generalization, it's just my experience. In another way, you could call it my truth.