Except it's not entirely true. There's a chance it might show up in a Dragon Annual, and there have been some article content taken from the DDI magazines and placed in actual books, such as into the DMG2 (off the top of my head).
It's not all inclusive, but not everything is a dead-end. My only gripe about so much being digital is that I'm still not happy with e-reader technology and electronic distribution models presented so far, but I still I still love the articles, the character creator, and the Compendium.