He presents an exhaustive history of reconnaissance units focused on their TO&E, their doctrine and their actual use with a few examples. His conclusion is that dedicated recon units are not needed as other formations can do this mission adequately. When reconnaissance units were light, commanders would not use them for fear of casualties, and regular mobile units would perform reconnaissance.
If recon units were made heavy then they would be used more often for missions such as defense or mobile reserve. Dedicated recon units, he says, are a legacy of cavalry. Cavalry made sense for recon because they moved faster but had less combat power than infantry. But mechanized combined arms formations do not give up combat power in exchange for their increased mobility; rather they pack a greater punch.
This reminds me of Archer Jones Art of War in the Western World. He divides all pre gunpowder units into four classes: foot or cavalry, and melee (heavy) or missiles (light) oriented. These categories collapsed with gunpowder, with all cavalry becoming light cavalry, good for recon. The motorized successor to light cavalry, he says, is not armored cars or light APCs but aircraft. This book seems to mostly confirm that loose analogy as aircraft do recon since WWI and ‘lighter’ versions of mechanized combined arms teams seem to be able to do what the heavy ones can just not as well.