Because third person limited has more than one while first person is strictly form the point of view of the main character no narration just the thoughts of the first person.
In third-person point of view, the author is narrating a story about the characters, referring to them by name or using the third-person pronouns “he,” “she,” and “they.” Unlike a first-person narrator, a third-person narrator is not a character within the story they tell.
