It's interesting how many people are in total denial that the issues even exist, despite all the evidence to the contrary. It's kind of obvious why, when you think about it.
If the tech industry has a diversity problem, then that kind of suggests that the people in tech are part of the problem. Most people don't think of themselves as being sexist or racist, and in fact have extremely negative ideas of what those things are. So when the problem is more subtle and doesn't imply that the people who are part of it are bad people, it's hard to make the argument because people quickly get angry.
For another example of this, take Anita Sarkeesian's videos about video games. There's an instant -1 flamebait mod - see how angry people are even at the mention of her name? She starts the videos by stating that it is fine to enjoy video games while also critiquing them - in other words playing and enjoying a game with very poor female characters doesn't make you a bad person, and she isn't suggesting that you are. But when you look at people's reactions, it's clear they see it as a personal attack on their character, because they feel guilt by association.