a friend of mine expained downvoting to me in a way that made a lot of sense. I'm gonna paraphrase what she said and apply it to this post.

when we express our lack of support for a post, it's usually about the information (content) the post contains, the reward the author is getting, or the wording, if it happens to be contrary to the beliefs of a community. for an example, hate speech.

we are engaging in what the free-market calls market forces - how society self-regulates, as opposed to relying on centralized governments to regulate our behavior for us. We regulate each other, and that's how societies and markets work when left alone.

I think the downside to this is social mores and popularity; the prepensity of a society to judge based on personal ethics, likes or dislikes, rather than by unbiased rules of conduct. We are trusting individuals in the community to be fair, which is a hit or miss proposition.

When enough people express their opinion on something in a similar manner, it becomes in affect the "ruling". society will continually respond to this self-regulation -- not all at once, but person by person.

The other downside to this is power, which in the hands of the wrong person is detrimental, especially if they are unstable or hold a grudge.