Why 90% of a First Draft is Doody

The phenomenally talented author John Green has said 90% of the words in his first draft are NOT in his final draft.

Which is really a huge amount of words to delete right? I mean, that's a daunting freaking number. That's the kind of number that makes you want to curl up, suck your thumb and not write again. Because WHAT WAS THE POINT then of the first draft????

The point? Well, it's just the process.

Now, I'm not going to claim to be an expert. But this is John Green we're talking about. And ...