Well, I can certainly accept that it's possible to overweight github as a hiring indicator, however that's not been my experience from either side of the interview, so I strongly suspect that if there's an optimum amount of attention to pay to services like github, most recruitment programs are on the 'too little' side rather than the 'too much'.
Yeah, while I agree with a lot in the article, I also agree with your generalization. Most companies are still looking for the boring "CS degree + 2 years experience, HR doesn't know what github is".
But there are also a lot of "hot" companies, of the sort that are talked about a lot on HN, that are pushing github as the end all be all.
The real point isn't about what the average company is doing, it's about which attitudes are sensible.
(Bias: I got my first job as a developer based on a combination of a non-technical friend's contacts and my github repos looking acceptable. I was three years out of grad school in the humanities at the time).