DocBook provides for more than just formatting. You can automatically build indexes, tables of contents, and links within the document or to outside. The Jade and OpenJade packages also let you export (I'll call it render from here on) DocBook to LaTeX, info, text, HTML, and RTF. From these basic formats, you can then create other formats such as MS Word, PostScript, PDF and so on. Programs like LyX allow you to write in TeX format, then export it as DocBook SGML and render from SGML to whatever you chose. In the end, DocBook is more concerned about the way elements work instead of the way they look. A big distinction,and one that will let you write faster, since you don't have to worry about placement of paragraphs, font sizes, font types, and so on.