I don't know exactly what you are getting at with this question, but as someone who lived before word processors, I can tell you what their advantages are. You can go back, reword something, improve spelling (the word processor may even direct your attention to misspelled words), and erase mistakes, and none of it will show on the final copy. You can edit a page many times and only use one sheet of paper, or none if you don't print it. You can electronically cut quotations, graphs, maps, photos and so on, and imbed them in your text. You can vary the font you use. If you write a lot of documents with a similar format, you can create templates.
If all this seems trite to you, I invite you to write a report, essay or letter on a manual typewriter sometime.