I disagree. If you want to review a candidate's code, GitHub is one of many useful tools to do so. Having code on GitHub does not require one to participate in its social features.
If GitHub lets you verify that someone is capable of writing code that you think is of high quality, is that not a useful tool to apply in a wide variety of circumstances?
The point of the article was looking at influencial people in GitHub, the ones for which an automated resume even make sense.
Now indeed, you can also look at the code that even regular people are producing. The problem here is that you filter people that uses GitHub as a code repository, storing learning material (i.e. rubbish), quick hack (i.e. dirty, no tests), ..., or people that use GitHub as a code portfolio with a selection of their best piece of code.
But really, whatever works for you. There was the same talk about LinkedIn first, then StackOverflow accounts back in the days and nowadays hardly anybody cares.
If GitHub lets you verify that someone is capable of writing code that you think is of high quality, is that not a useful tool to apply in a wide variety of circumstances?