PHP & XSLT question

I'm presently reading "Using XSLT" and have created their examples using PHP and sablotron to render HTML from XML and an XSL template. I understand the value of using XSLT to render XML, but what is the advantage or reasons for generating XML from a database and rendering it to HTML using XSLT over using templates in PHP to render the information directly from the database? Is it faster to read from written XSL files in some cases? Couldn't HTML includes be written and saved in the same way? -dg http://www.rexruff.com