For ebooks, we don't rely on the browser to know what to do with sloppy code, because the reader may be not a browser. It may be a Kindle or worse. So being abl

For ebooks, we don't rely on the browser to know what to do with sloppy code, because the reader may be not a browser. It may be a Kindle or worse. So being able to strictly validate is a benefit. Also, being able to use xml-based tools for editing and creating is a bonus.