When made a co-author you can type in the Buzzword document too! However some times its easier for the other co - authors or other members access to the file to see which author wrote what? So with a simple click of a button that sais "Color Distinction for Authors" or something along those lines will have the entire buzzword document text change into the color related to who wrote it ( a quick table of contents with which author is what color will show up too, or can be seen in the toolbar on the bottom). This will make largely community made documents easier to tell who wrote it, or just another easy tool to make the authors life easier (or anyone else using the tool).