Yup. Glad people are saying this. Hope companies are hearing it. (Also, I dunno if you can edit the title, but it's "predominantly".)The most impactful detriment to diversity in Silicon Valley is the idea of “culture fit.”
I'm pretty sure that most executives are fully aware that "culture fit" is just a thinly veiled policy of discrimination. Workers who fit into a brogrammer (work hard, party hard) culture or super active (outdoor adventures) culture are better for the bottom line. These "cultures" implicitly exclude workers with family commitments, chronic health issues, etc.
I have advised many tech companies through start ups and through IPOs and could not agree more. I had never heard the term "brogrammer" before but it fits perfectly into what a lot of start ups think they want. But in my experience the ones with a diversified workforce have done better. Something I have said many times is: Don't just hire people you want to go out drinking with. Personality is just as important as skill but having a range of experience is even more important. As companies mature so does their workforce. New ideas from youth are very useful but so is experienced management that does not blow their first million buying a strip joint instead of buying some blue chip stocks.