Networking is not just for extroverts. One on one time with friends, and small group networking is still valuable networking.
Sure, but it isn't as likely to get you new opportunities in new fields the way being extroverted is.
The extrovert has loads of low probability opportunities; they tend to be more varied due to the breadth of their networking.
The introvert is selling to people they know; if they get to the point where they are asking for the opportunity I predict they land a larger percentage than the extrovert. Because they’re drawn from a smaller network, however, they are also likely to be in narrower fields.