GitHub is focusing on the very bottom of the funnel. They are noticing the distribution of their employees doesn't match that of the larger population, then attempting to make it match. But what if the reason their company distribution doesn't match up is that the distribution of people with the requisite skills doesn't match up? They are trying to treat the symptoms of a supposed problem rather than the ailment itself, and putting themselves at a competitive disadvantage by doing so.

Affirmative action doesn't work, except for the short-term career prospects of those individuals lucky enough to profit from it, and the virtue-signalers who propose it.