I hate to break it to all the Real Warriors out there, but if the price of victory is dead and wounded rifle-carriers, we are in a poor position against polygamous cultures with resource economies, because they have lots of men to spare; and in a doubly poor position if they also embrace martyrdom.
Therefore a combined arms approach that plays to our strengths, not to doctrinaire rubbish of one arm being essential and the others merely support, in our only option.