I think your question is important and relevant...and I myself (over the past seven years) am still just finding my way in this "brave new world" of Internet discussions...
To me, the Internet is potentially a treasure because of the information and insights you can exchange with people all over the world, all different backgrounds...learning and growing. However, there are severe problems that you, Rooster, and others mention and those can cripple a Q/A site.
I am beginning to think the biggest obstacle is with moderation on Q/A sites, in finding skilled moderators. A moderator has to be almost a genius, and a psychologist too!
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I would like to see the Internet discussions take place on those important topics, but other than finding a site like this one where people are naturally open-minded, respectful and courteous, I don't know how to avoid all those very destructive problems.