In fact, a true meritocracy in a very competitive field is more likely to exacerbate the differences that already exist in society and result in an extremely uneven distribution. In a non-merit based industry uncle Bob can get a top job for his 3 children, and his friend's children regardless of gender, race, and any other characteristics. He can also appease reporters that criticize the distribution of his company and hire more people in the less represented populations to correct the problem. In a purely meritocratic field uncle Bob has no influence, no control, and each of the kids has to fight his or her way in. All uncle Bob can do is pay for the best education and the best opportunities for his children to compete in the meritocracy. To the extent that there are small inequalities among the population, those with the most resources will prepare their kids best to compete, and those kids will be over represented in the most competitive fields. The fact that the tech industry is dominated by white males only indicates that it is very competitive, and that white males historically have had a leg up in American society. A leg up that the meritocracy is quickly erasing.

Agreed. However, an uneven distribution of merit might still be a social problem; it might be indicative of vast inequality of opportunity for developing said merit. However, in this case, the problem is not one specific to silicon valley in any sense.