Actually, RSS feeds are also used as a defensive method of link building. YOAST makes a plugin for Wordpress that everyone should use (if they use wordpress), one of the features is inserting text and links into your RSS feed.

Obnoxious scraper sites use RSS feeds to populate their websites, they do not monitor the content, its all automated. By putting links and a citation in your RSS feeds, this lets you at least get a little benefit from their theft of your content.

Link Explorer shows feedburner and a couple other RSS agg sites as high value referring sites.