Board Thread:Suggestions/@comment-5381241-20140922154549/@comment-4825926-20140927101337

Often there can be a good reason for joining a conversation on someones Message Wall. Besides, even when we had Talk Pages, people would join in on conversations. If you really need to have a private conversation, dont use Message Walls. Use PM in chat, or emailing, or a super secret private wiki. And if you're unable to use anything else, then you can always just ask someone to leave

I would warrant a guess that most arguments like you're referring to are caused because of the subject matter, rather than the fact that someone "uninvited" turned up And in that case, people should use some common sense, not rely on a LMBW rule.