The narrator, who is the voice of the town in general, uses anecdotes to tell the story of Miss Emily's life as observed by the people around her. This technique is used to transcend time, from the time right before Miss Emily's death to her youth to the time around her father's death, etc. Because the narrator is the voice of the town, the story unfolds to the reader through the town's eyes, and thus their assumptions are the readers' own. For instance, when the narrator reports about the awful smell that pervaded the Grierson house, he/she includes she small detail that it started "a short time after her sweetheart - the one we believed would marry her - had deserted her." Like the townspeople, the reader does not discover that the source of the smell is the sweetheart's dead body until the very end of the story when the body is discovered.
I think its because the author wants there tto be more insight from the charactor that you wouldnt get for 2nd or 3rd person. You get to see what is in the charactors mind
