When I was young, and on the outside of my profession, I thought of IT as a sort of embedded, marvelous utopia, a land of high ideals and ferocious belief. It was - it still is - a sort of firelight to the widest-eyed moths of humanity, drawing in a lot of very intelligent, high-minded people. When I thought of it, it was easy to imagine the way a student would feel in a hundred years, reading about these hungry souls ripping a new era from a mass of copper and silicon. Heroic, in a very real way.
Historically, programming began as a largely female endeavor - the operators that wrote punchcards for the early computers were overwhelmingly female. It was viewed as, essentially, skilled clerical work. Only when software development became something we as a culture admired, found magical and creative, did it become a male profession. With this transition, and with the sudden meteoric growth of respect for technical careers, a culture grew up.
While the boundaries are loosening now, even today certain cultural elements are very much binding forces within the programming community - building cachet and understanding with other programmers is half technical acumen, but, in my experience, also has to do with trading the cachet of shared knowledge and experience. And this knowledge is largely not technical. The ability to tell and comprehend jokes on Star Wars, Douglas Adams, or Doctor Who, for example, are a quick way to find rapport in a technical community. These elements are, of themselves, seemingly harmless.
An acquaintance of mine - a far better programmer than I, and a genuinely nice, open-minded person - made a joke the other day that illuminated this. He was talking about a time management technique called Pomodoro which is very popular in the tech community, and how they were doing it in groups, calling it 'Bromodoro', because 'its like Pomodoro with your bro's.' The joke was meant to be tongue in cheek. The word bro, has a sort of 'oh-god' hipster ring to it that marks any use of it as not entirely serious (at least this is my experience - though as with any slang term, these borders of legitimacy can be murky). I wrote back, half-jokingly, to ask what they would call it if they had a woman working with them. He wrote back and said that 'sisses could be bros, too'.
But at some level there is a piece of our culture that says 'we are open minded, liberal people, and would love to have more women (or minorities, or GLBT people, or whatever) join our culture. Just as long as they don't change it.' In other words, diversity is great, as long as we all act the same.
Again, this isn't to suggest that the fellow who made the 'bro' comment was trying to send some 'boys only' vibe out, at all. But, I do think that technologists, as a culture, are comfortable with the vibrancy of our community, with its strong identificatory marks, and we sometimes assume that others will be happy to simply enter the culture as 'bros', as it were. Its the old issue of letting women (or minorities, or whatever) come in and be 'one of the guys' - even if they AREN'T 'one of the guys'. Again, this isn't meant to put a freeze on speech, its simply to point out that when we live in a culture that is very monolithic, it is easy to present a from that is less than welcoming to a polylithic world.
But then, again, if this is a revolution, this is how revolutions always are - they break the limits of the last regime, and then scramble in terror to build new ones, to make walls that let them understand the new world they've created, that protect them from the anarchy of a new social order. It doesn't mean that the revolution wasn't real, or the revolutionaries insincere. Its simply how humans work. Until the next revolution comes along and topples them.