Omitting needless words, however, does not mean cutting out every single word that is redundant in context. As we shall see, many omissible words earn their keep by preventing the reader from making a wrong turn as she navigates her way through the sentence.
I would like to ask question regarding the usage of idiom "earn their keep" in the above clause. "Earn one's keep" means "earn enough to pay for the basic necessities". From the context I derived that the author wants to say that sometimes it is useful and meaningful writing omissible words. Is the usage of this idiom in this context when we do not talk about people standard?