What's interesting about this is, I have always done what the author describes and I just assumed when people wrote (for example) an essay, they would outline all the points and the structure first and then go and fill in each section and refine it over time. Same with ideas and projects, I would do rough outlines, then add fidelity. Same with programing, I'll make an outline and go and refine it all. It's strange, I…
It really depends on the task/text at hand. With some things I set out to do, I know I want to reach a concrete goal, then it's easy to do an outline first with the finish point being the known goal, then fill out the middle-pieces.
But at other points, you're not 100% sure what the goal is. Then starting from the beginning and just going with the flow until you reach something that feels like the goal is the way to go, and you'll adjust as you go along.
Other times a mix between the two is optimal, where you think you knew what the goal was, but as you're half-way of filling out the outline, you see that another goal would be better fitted, and you adjust. Or you realize what the goal was all-along as you're nearing the finish, and you go back and adjust.
Basically, there is no single path/process that fits all types of problems or people even. You try out different things until you find the way(s) that fit you and the stuff you typically handle.