WordPress can be used as a platform in two ways: as a theme or plugin by extending WordPress functionality without modifying the core, or as a standalone application using BackPress, which provides WordPress core functionality as a PHP library. Some advantages of using WordPress as a platform include being comfortable with WordPress, compatibility with unknown server configurations or older PHP versions, and providing a quick prototype. Disadvantages include inexperience with WordPress, complex applications, requirements for newer PHP versions or multiple database support, or background processing needs.