As someone who is a programmer for 41 years, leads multiple open source projects, posts to github on a daily basis, and writes code every day I find this trend disturbing. I have interviewed for a job where I helped implement the compiler they use and I'm "not qualified for the job".
People ask me why I'm not in management. I've turned down several "promotions" in companies because I live to program. Why would I move from the top of my skill set to the bottom of a career I know nothing about?
So your advice is interesting but seems to have a target audience of recent graduates, not seasoned professionals. Look over your hiring record. I'm willing to bet that you have not hired anyone over 40, regardless of their github status.