The fact that there did used to be a lot more overt injustice is making a lot of people angry and resentful of any suggesting that there still might be a problem. This observation explains about 75% of Slashdot posts on the subject.
I don't think there's anyone who would claim that everything is perfect and I think the resentfulness is coming from having the same story pushed again and again. It would be one thing to argue that women and minorities in Silicon Valley are being paid less, but it's another to argue that not having a workforce that's exactly equal to the general population shows a lack of diversity. It would be rather silly to accuse the NFL, NBA, MLB, or NHL of struggling with diversity, and yet all of those have as much of an aberration as the tech field.
Also, you have to consider that from a man's perspective, merely being labeled a sexist at all, whether or not it is true is possibly career ending. Look at the recent shit-show controversy surrounding Tim Hunt or Matt Taylor for good examples of how out of hand it has gotten. The people who took offense and sounded their outrage are the reason there's such a backlash and why people don't even want to broach the subject. Most people aren't going to blow it up into a big deal, much like most people won't abuse you in a relationship, or most people aren't going to mug or assault you on the street, but it really only takes one to completely turn your life upside down.
When you have that kind of atmosphere, it's not conducive to debate at all. Even if you and I are both reasonable, it doesn't stop some third party from driving by and make accusations because what someone said doesn't jibe with their beliefs. There are some who would call me a racist and others who would like you as some kind of feminazi for yours just for daring to take sides.
So there is a massive push back against efforts to get diversity in tech, because if tech is doing badly then people in tech must be bad people, right? And I'm not a bad person, so the claim that there is a problem must be wrong.
I think a lot of the push back occurs because the solutions presented by the people who tend to take on these causes are unlikely to work. First they rest on the notion that a deviation from some magical number suggests that there is a problem rather than looking at whether qualified minorities are being treated worse. Here's a relevant quote from Thomas Sowell:
The idea that large statistical disparities between groups are unusual—and therefore suspicious—is commonplace, but only among those who have not bothered to study the history of racial, ethnic, and other groups in countries around the world. Among leading scholars who have in fact devoted years of research to such matters, a radically different picture emerges. Donald L. Horowitz of Duke University, at the end of a massive and masterful international study of ethnic groups—a study highly praised in scholarly journals—examined the idea of a society where groups are “proportionately represented” at different levels and in different sectors. He concluded that “few, if any, societies have ever approximated this description.”
However, the new wave of social justice sees this as a violation of a core tenet of their faith and therefore anyone who believes such a thing must be a racist. But let's assume that their belief is actually correct for the sake of argument. The article would still suck as it tends to suggest a top-down solution, in that a diversity problem in tech can be solved by simply hiring more minorities. Even if hiring standards are lowered to give preference to minorities, there simply aren't enough available candidates. Worse yet, it's likely to create even more racism/sexism/etc. as you can't expect your workforce to respect someone who was only hired to fill some kind of quota and honestly I can't say I would feel all that comfortable working somewhere if I knew I was hired for that reason.
If you want to actually have more diversity in the tech sector it means that we have to start at the bottom and work our way up and that means fixing inner-city schools and dealing with a whole host of other problems along the way, which given there basis in economic inequality means that this is going to be a difficult task, but you're not going to see as many African Americans, Latinos, or underrepresented Asian Americans join the tech sector when they grow up in poverty and don't have any interaction with computers or that kind of technology when they're younger. And even if you fix those problems, you won't see the results for decades.
The people in technology are largely tired of having this rammed down our throats. We've probably had more diversity-themed stories posted to Slashdot recently than just about any other topic, and it's almost always more of the same, typically written or posted by people who aren't even in technology. And when disagreement with that line can by met with some rather serious accusations, it just exacerbates the problem and makes tempers flare on both sides of the issue. If people want to do something to increase diversity, then they should go out and do it, but the people who write these articles rarely discuss something that they have done and seem to push the problem into the hands of someone else, who might not even consider it a real problem.
A lack of diversity itself doesn't automatically mean that there is a problem. It merely indicates something that should be examined, but again there are some people who no matter how much proof you could lay at their feet won't accept any answer that doesn't conform to their predetermined beliefs. It's really no different than a religion in many aspects and there are some members who are a bit more fanatical than others about it. The social justice movement has become rife with such individuals and they're not good people. The recent controversy over a Kimono exhibit at a museum in Boston is a good example of how warped and perverted the movement has become.
Doing good in the world doesn't require one to do it in the name of social justice. If you want to help or make something better, go and do so. But clinging to a label and pretending the movement hasn't been hijacked by some authoritarian hardliners and trying to defend them just because they're on the same team isn't going to do you any good.