How about shy people who have a hard time talking to new people? Who only feel comfortable after a couple of days and then they become very chatty? Aren't most developers like that?
Being able to simulate extroversion for short periods at need is a useful life skill for any introvert - I've found it invaluable in plenty of situations beyond just job interviews.
Selecting only based on chattiness is not good, but filtering out people who cannot even chat is probably a good thing from a company's point of view.