This is almost difficult to believe. Almost.
I always really struggle to imagine these sorts of things happening in a large, organised way. Allowing this sort of thing to go on in your business should be an enormous risk. It amounts to a conspiracy, and its hard to believe that any one employee with the interests of the business at heart would allow it to continue, much less that very many people in a group would, and its extremely difficult to swallow that someone on the level of CTO would fob this sort of thing off rather than crapping their pants and lighting fires up under arses to get it investigated and fixed.
The other part I find hard to believe is that anyone, let alone large numbers of people can put up with this sort of treatment at work for so long without taking very serious action. I don't mean going to HR, or reporting it to X, Y or Z organisation or authority - I mean really, seriously decisive action - e.g. force some director/owner to pay attention personally, and provide them evidence, and record how it goes in case they are part of the problem - however that ends you are in a very strong position to proceed, with the wrong outcome quit and /do the right thing/ and continue to pursue it for the sake of others - with the correct outcome the problem is solved. I'll concede that eventually in this retelling there are more serious efforts, but its not far enough, fast enough - and I struggle to believe that "working with smart people" or any other such thing would make up for it.
At the same time its all horribly believable... One reason being that its happening in Silicon Valley, and more generally the USA. Compared to my experiences of the UK and Europe, workers rights in the US are terrible, discrimination is rife and the legal system very strongly favours the privileged and wealthy. Don't get me wrong we have our problems of discrimination and poor workplaces too... but, especially for office workers and professionals, there are lots of incentives for employees and employers to put a stop to it, and they generally carry a very low risk.
Another reason its believable is that when you don't feel safe, have to make expenditure and/or rely on your income for survival I can appreciate not wanting to rock the boat with your employer. I think that is a very selfish and stupid attitude, especially when others will suffer for your inaction, but I can appreciate why people take such positions.
However, all that being said there is something here that really irks me. I've been in situations with horrible employers before and I've blabbed about it to the press, and you know what I did? I had evidence, and I published that evidence with my complaints. The author talks about having evidence in their retelling of events, yet doesn't provide it alongside. I'm not sure I'd ever feel comfortable attacking anyone for anything without some evidence - maybe she just didn't think to keep it personally and left it in a work mailbox (an engineer being /that/ sloppy though? hard to swallow still). Its nice to see other people coming forward and backing the claims up... but I'm still left with a niggling doubt because of this. There is always the possibility that people will try and abuse discrimination claims for financial gain... its not reasonable to discount that possibility without some evidence to the contrary (i.e that the claims are valid) - as much as its more social acceptable to not raise this issue.
Maybe I'm weird, but that first response from HR would have been given a response offering /one/ chance to get it right without any indication that its a single chance (threats are dumb), followed by a notification of my intent to expose their behaviour publically (again no threat, just polite notice). Some copy of the e-mail thread with a select personal details blocked out in black would be posted on the internet that evening... definitely not days, weeks or months later - after the fact.
Still, I'm more inclined to believe it, the way the story is so casually told as if the blog post is to satisfy people asking questions needing the same story to be told, to save time on answering them personally, and not to expose bad behaviour is ... well ... its just sad, but its believable. The impression I get is that the author doesn't really appreciate just how unacceptable this sort of thing is, and is resigned to having to live with it... :(