Ecommerce: Catalogers and RSS

Dave Czarnecki has a post asking why catalogers can’t skip the glossy paper editions and go straight to RSS feeds.
Why not, indeed?
The questions have to do with how.
Bonus links: Paul Katcher’s got a round up of online shopping guides from the big guys. I’ve seen a lot of smaller guides as well–including the one from Cool Hunting, which I backed off buying but REALLY want(their ecommerce thing seems kludgy).