I am reading [Learn Python the Hard Way](http://learnpythonthehardway.org/book/) by Zed Shaw. In [this lesson](http://learnpythonthehardway.org/book/ex36.html) he writes: "Every `if-statement` must have an `else`."

What are the benefits of ending every `if-statement` with an `else`? Are there any legitimate reasons not to end an `if-statement` with an `else`?