Modern technology has given independent directors a high quality camcorder in their pocket.  The ability to capture high definition video on a whim has never been easier.  However, the one disadvantage would be the sound.  On your iPhone, or even a good quality camera, the microphone will pick up unwanted noise, and make crucial conversations difficult to hear.  What makes or break a film? Can the viewer hear and understand the pivotal parts of the dialog?  Professionally released films have this dialog re-recorded in a controlled environment.  This many times is the difference between an amateur recording, and an award winning film.