If I want to play on the living boards of this website, it starts to become really time consuming referencing everything you choose from the books you bought with the update you downloaded and printed out.
Why would you want to print the updates out to reference them? Having it up on the computer means you can search through the entire thing in an instant. Or you could make any sort of marking in the book next to powers, feats or items that have been updated. And even with neither of those steps taken, the errata is organized well.
So yes, DDI makes it amazingly easy, but I just don't see the difficulty in doing without it. But maybe I'm just not seeing it for some reason.