Whether it was intended to be satirical or not, Mark's post 'Leave RSS alone' illustrates perfectly the legacy of the link-blogger in RSS.
Designed for easy syndication of weblogs that pointed to other interesting pages, RSS contains a <link> tag that points to the external page, a <description> tag that contains a brief description, plus a title and a timestamp.
As it became a popular format for providing more-than-weekly information updates, people adjusted the format to their own needs, including making the <link> tag point to the item on their own site. News aggregators took account of this, with the result that anyone trying to conform strictly to the original RSS specification now has an fairly unusable feed. Hence the need for Echo.