If you think this is much ado about nothing, consider this: the subtle sexist parts of your company's culture will turn off any qualified woman from working there.
And we all know how EASY it is to hire in Silicon Valley these days.
I'd also like to add, one of the most positive experiences in my startup life was working for Brian Sugar and Lisa Sugar at Sugar, Inc.. This was my first job at a proper startup and as a male I was in the minority.
I joined as #10 or so, and the first non-founding engineer. One third of the founding team were female. The second engineer we hired was Lydia Wagner.
From #10 to #30 or so I think I was one of only two or three male hires.
The stereotypical Silicon Valley startup is founded by N engineers, probably male, who graduated from college in the last 5 years.
Put those people in a tiny room for 10-14 hours a day, 6 days a week, for a year or two and it's kind of inevitable.
But it's also easy to stop if you're self-aware about it, and the founders make it a priority.
Also, guys (if I may be so bold), this thread is acting as an existence proof for the point the article is making.