I only found the voting system to be a serious impediment for submitting content, not commenting. I just recently got my first truly visible post on reddit and it certainly felt quite satisfying. Even with that I can't be bothered to do actual posts. I don't much care about comment karma as comments have a much smaller target audience, if the person you reply to and the few people following the relevant subthread see it then it's good enough. The actual rewarding moments with comments (not just reddit) were rare. Every once in a while someone would reply on how useful/comprehensive/opinion shifting my comment was and it made it worthwhile all over again. As for the actual topic here I don't think reddit had any influence on my ability to hold a reasoned discussion. I'm not good at that, all I can do is withold my unreasonable, and "unreasonable", comments. Reddit definitely didn't encourage such self censorship but sometimes people would find value in my unreasonablness so I can't say it is a bad thing.