There's also a difference in how you approach the task. Writing with pen and paper is physically demanding and unforgiving of mistakes. Editing is a pain in the arse. So it's better to have a good idea of what you're going to write, which implies a thorough understanding of the ideas behind it.
But with a computer, you can do a brain dump and it's easy to edit afterwards. Less preparation, less thinking, is required. It's not an improvement.