...instead of using the Atom syndication format?
Atom is a well-defined, general-purpose XML syndication format. RSS is fractured into four different versions. All the m
Because the developers of sed sights got reemed from their marketing manager that they were "excluding" people by not providing rss. Since Mr. Marketing has never heard of Atom, you just provide both.
If you are restfully implementing it, its not a big deal to just do both and not get yelled at by other departments.