Unlike a third person story, a story in first person allows you to understand what the character is feeling and only what the main character is feeling. You won't learn what the guy across the street really feels. If the story is in Bob's point of view, you will understand what Bob feels, what he sees, and how he thinks. You will not understand how Sally down the street feels. Sure, maybe Bob will learn a little about Sally, but if Sally says something, Bon will interpret what she just said in his own way. I could be wrong but that's my opinion.
