> But if the numbers of qualified candidates vary by a factor of 100 (how many black vs white or asian CS PhDs are coming out of the pipeline) - why is the lack of diversity a problem of the industry?

Where one of the driving factors beyond product development in the industry is "scratch your own itch and scale it out", lack of diversity of background (of which sex and race/ethnicity are components, but not the only important components) means lost potential markets, so its in the interests of those who want to invest in the new markets for the industry (e.g., most of the big players in the industry, and most of the investors in big and small players in the industry) to invest in broadening the funnel. It is, if not a problem of the industry, a problem for the industry.

(It also could be a symptom of a problem of the industry in which the industry itself takes action, without realizing the effect, which narrows its funnel, reduces the supply of talent attracted to the industry, and drives up costs.)