I disagree with his statement. I'm also counting SLDL's and other variations as a form of deadlifting though, and without them, it would be much more difficult to work the hip and hamstrings within their natural boundaries. Some do say there is no point in doing conventional deadlifts for higher reps though so
For myself, I rank deadlifts higher purely on the notion that I'm getting more work done within a single exercise than with squats. As I'm improving my grip strength while working my traps as well as the entire posterior chain.