Tech is only the thing that all of these incidents have in common if you include only tech companies in your survey.
Obviously, a site like hacker news will be reporting stories about tech companies far more often than other kinds of businesses.
As unfortunate as it is, businesses produce a lot of technology and hire most of the people working in tech on a daily basis. Even if I don't like it, those businesses are a part of the field I'm in and what they do affects me, esp. if they are contributing to alienating women who already have a hard time breaking into or working in tech.
It would be interesting to see the breakdown of HN readership. I always assumed a large portion are YC companies and other startups who would be able to relate to these kinds of posts.
If Uber started putting out sexist advertising, would that reflect poorly on professional drivers?