The importance of The Open Graph protocol is most often overlooked by web developers, but if they actually paid attention they would realize that it enables any web page to become a rich object in a social graph. For example, Facebook uses this technology so that any web page will have the same functionality as any other object on Facebook. The social graph provides the opportunity to include information and present it without having to combine many different technologies and schemas, even though they exist.
Search engine ranking relies heavily on data provided by the website, behind the scenes the web developer is the organization that dispatches this information so that search engines like Google can find the relevance in a more streamlined sense such that it will increase the rankings of the website providing the data. Existing websites can implement the proper tags, however when you have a platform that does it all for you there is no point in re-creating the wheel so to speak.