@aral Firefox still has the RSS feed button, it's just not in the default UI.
Also some (mostly commercial) sites do deliver tracking pixels linked from their RSS feeds, which kinda defeats the idea of not being tracked...
Some still publish their feeds through FeedBurner, providing usage information for the Google surveillance machine. Fat RSS feeds do create quite a bit of traffic on popular sites, as each client reloads the full file on each access... No real incremental updates...