Regardless, it's for the same reasons that the NFL and NBA are 'hostile' to Asians, Indians, and any other underrepresented group: they're not. It's just a function of what people are culturally exposed to growing up and what we're conditioned to see.
It's silly to think a community that openly accepts whites, Asians, and Indians is hostile to blacks because we're a wee bit darker. Go to a black neighborhood and ask how many startups failed or people who gave up programming because they felt the community was hostile to them. It even sounds silly, right?
I'm black and the only reason I'm involved in the tech community is because my mom started working at AT&T 40+ years ago as a punch card operator and worked her way up. If she hadn't brought her work computer home when I was a kid in the 90's I probably wouldn't have fallen in love with computers. She also set aside the money to buy me a computer on a 5-year Sears layaway plan or something crazy like that (BTW who buys a computer at Sears?! This guy). She could barely afford it, but it was important to her because she knew what it meant. And she only knew it because she unintentionally ended up in the tech world.
Culture, exposure, and financial ability are the primary factors in my experience.
Might there be some discrimination? Sure. Everybody encounters discrimination at some point, some more than others, but such is life. What's sad is when people expect discrimination so they tend to 'see' it everywhere.
I've actually never heard a woman or another black person complain about discrimination in this community and I've never seen it myself. I've also never thought about it until now, which is a good sign, but maybe I'm just lucky. YMMV.