Atom was created because the RSS people refused to fix the ambiguities with RSS. Almost immediately after Atom was finalized, the RSS people changed their mind and fixed the big issues. So now there's really not much reason to choose Atom instead of RSS. Atom ended up being a big waste of time; actually, it wasn't a mere waste of time, it is actually harmful. Now everybody who deals with feeds has to deal with 4 kinds of RSS + Atom, instead of just 4 kinds of RSS.