When collaborative sites have moderation functions to prevent a ‘free for all’, does this defeat the purpose?

OK so the most obvious collaborative website is Wikipedia. Bruns comments about the importance of creating a "balance between openness and structure." I personally think there has to be restrictions put in place in order to refrain from people feeling alienated, insulted or offended. I don't think it defeats the purpose because there is plenty for people to talk/write about without being offensive towards others. It's important that people express and share their views however i do think its pointless if it's going to result in encouraging world wide issues such as racism. People will not benefit in the long term from published articles like this.