I saw video by Thad Martin from Acquia regarding selling Drupal. It's amazing. I love it. this is probably the best video explaining Why Drupal. He has shared an awesome analogy that Drupal is like a Lego, and Drupal developer can deliver almost anything using Drupal, if having proper approach. And drag-n-drop option to move blocks on the page that is available from Drupal 8 makes it even more similar to Lego. Drop in and create your online Universe with Drupal using best practices of assembling web experience. There is an amazing long list of domains and long list of website types that could be delivered on Drupal.