By separating the layout from the content, web site creation and maintenance are simplified. Using templates a site wide layout change can be performed by editing a single file. Additionally the content creation is further simplied by removing the need to worry about the layout.
Writers focus on creating content consisting of straight text or very simple html.
Then as the page is generated the content is placed in the context of the page template. This allows a web team to split up the duties into manageable items. Authors, writers, and typists can create content, while web designers can focus on creating a set of site wide templates. The process is modeled after that of a newspaper publisher where a team of people with different skills continuously create a new edition day after day. Writers create content, layout editors design the style of the pages, and finally everything gets reviewed by the senior editor.