It's not a rule at all. We don't have to lock the threads when the users want. It's just that we choose to do so. But I agree every thread is different, the example you gave of where a 16 page discussion, it depends on the circumstances really but those types of locks are generally quite rare and I suppose it was down to the mod on what to do. But what was stopping you from making a new thread on the subject, in that instance?