To paraphrase Mr. Twain:

Sometimes, the difference between the right word and the almost right word is the difference between going down in history and going down in flames.

Who can benefit from keeping this book within easy reach?

Everyone who writes for others to read! When you write, for whatever reason, your written words represent you to clients, superiors, peers, employees, and, perhaps, the world at large. What you write and how you write it represents you in the minds of your readers. You shouldn't be satisfied to appear in public in linguistic disarray any more than you would in sartorial slovenliness.