Why does the author write the novel from one perspective?

Holden Caulfield narrates in the first person. I think part of the major draw of this book is Holden himself. He is smart, cynical, sarcastic, immature and mature. It is these ironies and paradoxes that make Holden so interesting and fun to see life through. Much of what Holden's commentary is darkly cynical yet there is some universal truth in it. Many of us are hypocritical and much of the time we do not even know it. Still the human experience is a complex matter and watching Holden break it down to right and wrong is both entertaining and interesting.