That quote may sound vaguely creepy, but fundamentally he's got a good point. The most brutal wars tend to be wars where both sides are roughly evenly matched. WW1 and WW2 were so deadly because both alliances consisted of several industrialized nations. We're lucky that we haven't seen total war between major industrial powers since that time: https://www.youtube.com/watch?v=DwKPFT-RioU