Zinsser says, speaking of writing, "Be grateful for everything you can throw away" (16). Why?

In writing you want your paper to be the most informative and interesting as it can be. Sometimes we add too much information, to try to add to it, but in general we don't need the extra filler. Writing is a mixture of adding just enough information and leaving just enough out. Filler is a big no-no. I have read books that have great content, and a good theme to it, but is impossible to read because of all the extra words they add. We have to be grateful for the things we can leave out, since having too much is usually better than not having enough. Taking something out of your piece just means that it's strong enough to stand by itself without the help of the filler.