I have noticed that some of the obstacles you face when discussing any subject is to stay in dialogue, specially when discussing on internet.  One of the feelings you constantly battle are the feeling of being threatened.
When you start being threatened you start to protect yourself either by going to silence or violence. Silence is when you stop adding to the dialogue since you dont want to be regarded as stupid or you feel that the person you talk to is not worth your opinion. Violence is when you stop listening and start acting out your feelings.
We are complex beings, we can have complex thoughts and even conflicting thoughts when we speak or listen, many of these thoughts are feelings that is constantly in the way of listening. So in a conversation you are interpreting what the person is saying by adding your own feelings to the mix, this means that the outcome could be that an innocent question from one person makes you feel threatened and you cut him off or that you respond totally different with another person. 
When we are having a conversation face to face, our bodies is also adding to the conversation; Angry, sad, afraid, stressed, calm, happy, and so on. This is of course missed in the written language and is a huge source of misunderstanding and why so many internet forums always seems to derail. There is also a culture of using Command and Conquer methods, which makes it hard for even the most balanced person to not loose his temper and go to silence or violence