When in the act of writing, absorbed by the process and furor of creation, word choice can sometimes take second place to the story one is trying to tell. When swept up in the work of defining characters, story arc, plot, etc., the author can overlook things such as extraneous words.
That’s why editors exist! We see the words, the sentence, the paragraph, as individual entities as well as pieces of the whole. Each word is examined for its purpose as well as its tone, its function and its form. Editors are there to see the best possible way to present the author’s words so that they shine.