'...if a person A is a rightist and the person B is a leftist, A's opinions become even more rightist in the course of the debate, and B's opinions become even more leftist.'
This is a good observation, often I take up a contrarian view for the sake of debate, but generally, I view debates as a constructive dialogue, not as a battle. So I often refrain from 'strict' opinions, I try to stay open-minded, and use words like 'I think' or 'it seems to me'. My tone only gets a little 'stricter' when people become angry or irrational.
In general I am unwilling to participate any debates, or even serious conversations
This is a little sad because I think you have a lot to offer, but the fact that you got involved in this discussion shows that you felt comfortable doing so. I would like to hear your thoughts more but of course only if you want to share them. It's nice to know there are other leftists here.
I hope you're well.