As I just replied to another user, paraphrasing this: downvotes might be perceived as the community self-policing, but if you visit r/vegan you’ll see how that can make a community hostile. I’m a vegan and I can’t fucking stand that place. If you have an alternative opinion, prepare to wind up on the top of controversial, where the mob has a field day.
I think some sub’s had the right idea by limiting the lower voting karma to 0. Another downside is it essentially paints a target for the community before an individual has formed an opinion. It generate the hive mind we should be avoiding.