I agree with the Fabian's post and I totally disagree with what Konrad says in his answer here. The purpose of being a skeptic is to improve the net quality of information people are exposed to.
Linking to pseudoscience, paranormal and other nonsense information gives that information a boost in Google and other search engines. This makes it more visible to the general public - precisely the opposite result of that goal. And because of the nature of search engines there is no guarantee that the boosted site will appear along side the corresponding question in the results. (i.e. We are boosting the original bad information, but there is no guarantee the people who see it will also come here and see the correction).
In fact, the problem is particularly bad with this site and with particularly fringe ideas. stackexchange.com has a pretty good PageRank. Many of these ideas are espoused on tiny websites that receive little or no other notice across the web. Linking to them from this domain can represent a tremendous boost to their visibility.
I do not see at all how nofollow "destroys the internet". I think comparing this to price fixing is patently ridiculous. A nofollowed link is still a link, a person can still click it, they can still see the original content. The original site can still derive ad revenue from those clicks and have a full opportunity to convince and solicit that user with ideas or sales.
I think it is precisely the opposite - the web has a flaw in it, and nofollow repairs that. The flaw is the way links are used by search engines - as a positive link only. Since a search engine can only consider a bare link as an endorsement, we have no way to indicate disapproval of content.
We do not owe other sites boosts in search engines. There is no obligation to us to help publicize the very material we are debunking. That obligation falls upon the people who want to push those ideas, and they are certainly free to get as many non-nofollowed links to their content (on other websites) as they wish to. It's not that hard, there are literally billions of websites that they can try to get to links on.
For more information: I have written about this multiple times on my blog and on randi.org.