While the title of this message may seem extreme, there are many times when it is relevant in project management. One example is in the area of requirements. Project requirements are always in written form. In the field of project management there is no such thing as a verbal project requirement.
The following text was taken from Chapter Twenty in the “Field Guide to Project Management”. The authors Francis M Webster, Jr. and Stephen D. Owens state, "the written document provides instructions, restates previous instructions, conveys importance to the message, and helps the project manager to cover their tracks".
The authors also make the point that that "e-mail isn't always enough and can get you in trouble faster and with more people". As we all know from experience, e-mail usually isn't given enough thought before it is sent which can lead to messages being misinterpreted and having unintended consequences.
A project manager that is doing his or her job will formally document all items that are important and relevant to supporting a project's triple constraints (Time, Cost, Quality).