No social news site is going to be perfect. If it's people that are writing comments, some comments will be good and some will be bad. Read them and decide for yourself. If a comment hurts your feelings, get over it. If you like a comment, upvote it, and help other people find the best comments. Really, I kind of get tired of reading stuff like this because there is always some subtext to it. "mean-spirited" usually…
I think a big problem with a "harsh debate climate" is that the people who can provide real value with experience, knowledge and insight will stay away. For different reasons like personal, professional or just disinterest. That will in turn attract more people who enjoy a harsher debate, which most (if not all) of the time are less enlightened. Or as the saying goes "Never argue with an idiot. They will drag you dow…
An overly civil debate climate, viewed as a "circle jerk", might also keep some valuable contributors away. Whether that is a good thing or not is up for debate of some sort.