Most writers don’t make great editors or proofreaders, especially of their own stuff. Writers are always revising. I know every time I go back to something I wrote, hours or even months before, I see things that need revision—and usually, not just “touching up.” At the same time, writers are loath to criticize “their baby.” Neither one of these traits makes for good editing, which should neither change the meaning of what is written nor accept every word as scripture. Good editors respect the writer’s work by endeavoring to make the meaning more clear and to see where the writer has veered from his or her own (one would hope) obvious intention.
Editor’s are also ruthless about editorial style. If the company has decided on a house style, then that’s that, no matter what liberties the writer thinks are permissible in the cause of writing style, in the sense of a well crafted sentence. The good editor also is able to see where a writer may be assuming too much or too little knowledge on the part of the user of the documentation. Where do acronyms, although spelled out in the beginning of a document, need to be clarified again because the distance (for the reader) between the original definition and the next use of the acronym is just too great?
The editor provides not only this rule-based help but also has the advantage of perspective. Editors are not married to the composition as writers must be. Think of them as the marriage counselors mediating between writers and their work. Writers sometimes need reassurance that they’ve done well (the “I know that this is the worst XYZ ever!” syndrome), and sometimes they need to be asked hard questions like “What do you mean when you say…? Good editors are both understanding and objective.
Finally, in most companies, editors are left to do the drudgery of proofreading. Writers are incapable of proofing their writing, because they will inevitably read what they think they wrote or get caught up in more revision—which cause extra spaces, double articles (“the a customer is always right!”)—rather than paying attention to the word by word correctness of a document. What’s true in a court of law is true in the courtroom of writing: The defendant (writer) who is his own lawyer (proofreader) has a fool for a client.Google+