I think that the internet, by its own nature, self-segregates people. I might not have data to back this up, but it is apparent that people go online to ratify their own views, rather than to listen to others.
I have also left reddit, mostly because the discussion around any controversial topic is toxic. Toxic. At least here you get the occasional moderates who are willing to actually have a discussion, where they try to check their assumptions and the logical leaps that they make to justify a point.
But to answer your question, I simply say that perhaps HN is the best place to have this type of discussions. Simply because politics, important societal issues, etc permeate our lives, including the technology that we use. In that sense, a good way to ponder about these issues is not to face them directly, but to deal with them as they arise within the confines of our daily lives.
By the way, I have made plenty of weird assumptions and assertions in this post, and so have you, and the weird thing is that instead of focusing on those issues, it is likely that I would feel personally attacked if I were shown to be wrong. That is part of being human, but it is also ultimately why talking about any issue is hard:
critical thinking is hard, and uncomfortable, and a concept that everyone talks about but that nobody is really willing to utilize.