Eh, I have trouble extending the concept of "censorship" of the internet to private websites deciding what can go on their own sites. HN flags and kills threads too. That's not censorship, because HN is Y Combinator's website, so they can pick and choose what kind of content they do and don't want discussed on their site. I could imagine saying, "[HN | Reddit | Slashdot | whatever] is running their site in a way I disagree with", but it's hard for me to imagine complaining that they are censoring me, and getting on some kind of high horse about "free speech", as a bunch of people on this subject seem to be doing.

If something really becomes a central medium of communication such that it's hard to avoid it, like the telephone system, internet infrastructure (backbones, DNS, etc.), and so on, then it starts to be a different issue imo. Then regulation as some kind of content-neutral common carrier might be in order. But does Reddit really play such a role? Twitter or Facebook seem closer to filling such a role, if we were going to pick one of those platforms.