Perhaps many introverts become very cynical about extroverts because of these particular monsters. Though in general, extroverts, like I said, don't really bother me and I quite like them most of the time.
Especially if somone has one (or for the lucky, several) in their family or in-law family. To grow up as introvert being invaded by one of these is hell.
Especially when the introvert in the situation is still young because it makes you gun shy of anyone who seems extroverted so you close off, stay quiet, try to hide and that makes you look like you have a problem and the extroverts then try to "help" you and then it sends you even further inside. Can become a self-fulfilling thing.