Meh I don't agree, coming from someone who doesn't post that often I still think that people should be able to post as long as it is relevant to the topic and or brings something new to the discussion.
Obviously there are people who spam but the mods deal with it, however what happens to normal users who are experienced for example scripters who may want to or be capable of replying to more then 15 topics? If this limit was introduced then they would be forced to post on threads they deemed more important which leaves questions unanswered on other topics.