Not much unless you have strong editorial leadership, but then you run into the problem of what if the editors don't like something someone posted, assuming it's true, and the editors delete or modify the post, then what?. But without editors it'll basically become a screaming match between the extremes. Even here you can find that, generally I take the high road and just drop out when that happens, and I think a lot of people who would be willing to discuss an issue and respect the other side do the same. Once the screaming starts they leave.
Wikipedia, the most popular wiki website till date, has become a global success. Wikipedia is a set of collaboratively edited encyclopedic articles anyone can contribute to. What can we learn from Wikipedia and other wiki websites when it comes to improving the political system of our countries?