There's a reason many successful writers from David Foster Wallace to JK Rowling opt to write with pen and paper — longhand is intentionally slower than the click-clack of a keyboard. (Note: I do encourage everyone to blog as another instrument of expression and a place to show your work).
When your mind moves as fast as the computer keys, you tend to overproduce. It's like taking down all the professor's notes in class. While everything gets consumed none of the words have staying power. There's no such thing as a tranquil flood of information.
It's true: the more you get down, the more you have to play with. They even say to write continuously to push out our ideas.
But acceleration can reduce the quality of your prose. The neurons need time to connect to each other in order to talk with more clarity.
Whether you're writing via keyboard or analog, all writing is in the edit. Having a writing process just makes it easier.