How would the interviewer know that you wrote the code on your github?
I mean what if I'm applying for jobs using someone else's resume? What's stopping me from having my coder buddy do the phone screen for me? Why don't I just list a bunch of experience at companies that went under... Unverifiable. Use a bunch of references that are actually my roommate and my dad with Google voice numbers.
At a certain point you just have to take things at face value. A GitHub is just as verifiable as every part of your resume that's not a school you went to or your identity
I do think the original article suggests that if employers put a lot of stock in github, the coding academy people would quickly have the "best" github pages.