Laura Hazard Owen, writing for Paid Content, identifies why the "social media has killed RSS" idea doesn't apply to many of us:
The best thing about Google Reader, from my point of view, is that it allows me to scan a lot of information quickly, with the assurance that I'm not missing anything. That's why, for me, it fills a completely different role than the (equally useful) Twitter does. Twitter provides a snapshot of a moment in time, and you're likely to miss tweets as they whiz by; Google Reader stores everything. The search on Google Reader is also vastly better than the search on Twitter, and it goes back indefinitely.
Twitter is where I go to find out what's happening. My RSS reader is where I go to become informed.