Officially: no politics. That rule is not always enforced. Likely: the owners of ycombinator and hackernews have very specific views and connections to people

Officially: no politics. That rule is not always enforced. Likely: the owners of ycombinator and hackernews have very specific views and connections to people in the tech industry with very specific views. Tech Bros are taking over, and ycombinator is squarely in the tech-bro camp -- that's the point of the site!