Thanks for sharing the threads. I always think that downvoting is for discouraging bad arguments from DH0 to DH3 [1] (for discussion quality as you mentioned). Now I realize that even convincing arguments at DH6 can be downvoted as long as one disagrees with it.
Also, if one's sick of discussing a topic, s/he can simply don't read about or discuss it. Why prevent others from discussing it?