These posts were typically defended in two ways: "politics affects nerds, therefore it is a legitimate topic" Bogus in my opinion, because I can go anywhere to get general politics talk, Slashdot derived value from being nerd/tech-specific; and second, "the motto is news for nerds, stuff that matters--politics matter, therefore it is on-topic"--for crying out loud, it was joking on the fact that gadget news or who is in the new sci-fi movie is largely inconsequential. The latter may not apply to here, but the former can, reframed as "this affects the tech/VC/whatever community, therefore it is relevant." It might be, but if you let it become the focus of the site, it will attract posters who would rather generate heat, and they will overwhelm the posters who generate light and would rather not spend their time arguing.
I don't exempt myself from this, I am a relative latecomer to HN. I catch myself many times resisting posting because I don't want to help this place to become another Slashdot. I know I'm doing it right now and I'm sorry :-(