W3C compliance can have a positive impact on search engine rankings. It’s fair to conclude if code works well for the visitors and browsers, it can only benefit your efforts with the search engines. So, why would one take the risk of having bad Web site code, if good Web site code will help visitors and search engine spiders alike?
A CMS after all, is an application which is intended to allow less technical individuals to update, edit and manage content on a Web site without necessarily being knowledgeable of coding or Web site programming. Having a CMS at the fingertips of internal staff allows for easy and instantaneous Web site maintenance. Making sure your CMS is search engine friendly and W3C compliant also aids to insure your website will be technically effective as well.