Nofollow was introduced in January 2005, so it's been around for a while. While the first wide-scale deployment was on blog comments and similar content management systems, it was always a general mechanism that Google respected. In fact, the very first nofollow links on the web were not placed on a blog or a forum. They were on my school home page. I put them there for testing in late 2004--they're still there, in fact.

In this instance, if someone is running a consumer complaint site that is going to be linking to a bunch of semi-scuzzy businesses, it's reasonable for that specific niche of sites to ask themselves whether they want to add rel=nofollow on the links to the businesses that are being complained about.