The problem is that with the glut of document declaring strict conformance but failing to be, fallback mechanisms had to be implemented, making it like a two pa

The problem is that with the glut of document declaring strict conformance but failing to be, fallback mechanisms had to be implemented, making it like a two pass parser, where if strict fails, you reparse in non strict. In the end slightly more complex, and definitely slower. Anything more would be paraphrasing http://www.webdevout.net/articles/beware-of-xhtml http://www.webdevout.net/articles/beware-of-xhtml