Reasonable limit could be a good idea, but it brings lot of questions.
How much is the “reasonable limit”? What If someone would like to ask something related to that topic that wasn’t answers yet? What If someone posts a comment and the author of the thread won’t be able to answer because of the limit….etc.

Right now there is no need to set the limit, since we don’t have a post with more than 100 comments. We’ll see how it goes and once there are more posts with lot of comments, we can reconsider this.

-- Michal, http://WoodworkingWeb.com