Hello,
The WYSIWYG feature can be described as (http://www.phpdocx.com/news/post/phpdocx-v6-0-release-notes/208):
Many improvements to create a WYSIWYG editor for generating DOCX or PDF files. Support for new styles and tags in HTML to DOCX conversion. It includes the recommended configuration for CKEditor (http://ckeditor.com).
As you can read, it's the recommended configuration, and new improvements, to create a HTML WYSIWYG editor that its output can be transformed to DOCX or PDF.
Regards.