I always thought the same as the OP, especially Kevin Levrone. I've never seen a pic of him deadlifting, or Flex wheeler (good lower back though), Cormier, Dillet. In contrast, Mike Francois had one of the sickest looking lower backs ever. Those pics of him deadlifting in Flex were very inspirational.
Levrone also did not know how to present his back while posing. He never flexed the lower back making it look non-existent. Even Yates said that he had stopped deadlifting heavy for years - makes you wonder how his back would've looked if he kept on.