I mean, I tend to lean towards the more laissez faire approach to documentary making myself, but come on- let's not fool ourselves. There is no authenticity of any moment, regardless of whether it's being voiced over, or "unfolding before our eyes"... it all has an agenda, or 'statement' if you prefer a less loaded term. 14 seconds of silence or stammering might feel very real, but I feel simply the act of editing, hell, the act of picking up a camera and deciding "I'm going to document THIS" already kills any authenticity or objectivity. Don't get me wrong, I love documentaries, and like I said I have my personal biases as well... but I don't necessarily see one approach as truly being better, or more authentic than the other.

And on a more practical note... sometimes you just need narration. Take nature documentaries for example- It's not that I need someone holding my hand and telling me "see the lions are teaming up on the antelope" or anything like that... but sometimes there's no context to really understand what you're seeing... and the animals sure as hell aren't going to explain it to you.