You see this a lot in these kinds of discussions, but I can guarantee you will overlook a lot (most?) of excellent developers as many can't open source code (due to employment contract) or just don't really want to be coding 24/7 when their jobs fulfil and challenge them already and they have family/friends/sports/whatever to do outside work.

These seems to be a trend from younger developers from what I've seen, which assume every developer will have a GitHub account to show (like young non-developers nowadays can phantom people that don't use facebook or don't have a smartphone ;)