Why use an online Content Management System like Drupal?

Capabilities of a Content Management System

From wikipedia.org/wiki/Web_content_management_system

Automated templates
Create standard output templates (usually HTML and XML) that can be automatically applied to new and existing content, allowing the appearance of all content to be changed from one central place.
Easily editable content
Once content is separated from the visual presentation of a site, it usually becomes much easier and quicker to edit and manipulate. Most WCMS software includes WYSIWYG editing tools allowing non-technical individuals to create and edit content.
Scalable feature sets
Most WCMS software includes plug-ins or modules that can be easily installed to extend an existing site's functionality.
Web standards upgrades
Active WCMS software usually receives regular updates that include new feature sets and keep the system up to current web standards.
Workflow management
Workflow is the process of creating cycles of sequential and parallel tasks that must be accomplished in the CMS. For example, a content creator can submit a story, but it is not published until the copy editor cleans it up and the editor-in-chief approves it.
Delegation
Some CMS software allows for various user groups to have limited privileges over specific content on the website, spreading out the responsibility of content management.
Document management
CMS software may provide a means of managing the life cycle of a document from initial creation time, through revisions, publication, archive, and document destruction.
Content virtualization
CMS software may provide a means of allowing each user to work within a virtual copy of the entire Web site, document set, and/or code base. This enables changes to multiple interdependent resources to be viewed and/or executed in-context prior to submission.
Content syndication
CMS software often assists in content distribution by generating RSS and Atom data feeds to other systems. They may also e-mail users when updates are available as part of the workflow process.