I find it ironic you're accusing either me or the author of narrow-mindedness but your responses clearly indicate you haven't comprehended either of our points.
I do agree that you or your (extended) network don't know all the people worth knowing as there are always gems in random pool of people, but I think the odds are a bit better, at least from my own experience, finding them through the people in your network. How it usually pans out is that you ask your network "we look someone to do X, does anyone know anyone" and they ask their network and the loop continues until a name or a lead to a name comes up.
Hiring people you don't know opens you up to opportunities to expand your horizons and go in new directions. If a good culture fit means people you already know then you are incredibly narrow minded about culture.