According to DVD commentary, the reason why the episodes are non-canon is a trade-off for the writers. Writing three 7-minute segments was just too taxing for the writers, so it was proposed that they could do anything without worrying about continuity to appease them. The yearly Halloween special was named "Treehouse of Horror" because the original special depicted the Simpson children in their treehouse telling scary stories to one another. In later years, the series dropped the framing device of characters telling stories, but kept the Treehouse title.