Well that's easy. It's because the writer of the table has a blog, and therefore people who have blogs are obviously superior to those who don't.
I'm gonna assume that this "programmer competency matrix" is a "How similar are you to me?" matrix. Skill sets which the table author lacks are missing entirely, and for other skill sets the precise skill level which the author happens to have is the highest possible level.
I'm gonna assume that this "programmer competency matrix" is a "How similar are you to me?" matrix. Skill sets which the table author lacks are missing entirely, and for other skill sets the precise skill level which the author happens to have is the highest possible level.