History is a useful antidote to “one best rifle” thinking. The recurring lesson from antiquity through WWII and the Cold War is that weapons are optimized for doctrine and terrain, not universal superiority.
WWII alone shows this: the U.S. Garand excelled at mid-range infantry fire, the Germans fielded a spectrum from bolt guns to the StG 44 as they learned hard lessons about volume of fire, and special-purpose roles (paratroops, commandos, raiders) constantly traded power for handling. Postwar, NATO’s 7.62x51 era reflects Cold War assumptions about longer engagement distances and machine-gun-centric doctrine; then Vietnam and later conflicts pushed many forces back toward lighter intermediate cartridges to carry more ammo and control burst/rapid fire.
Modern special operations is the same pattern: the “best” rifle is whatever matches the unit’s mission set—CQB and vehicle work push shorter barrels and suppressors; rural mountainous work pushes more reach and barrier performance. The platform families (AR pattern in 5.56, AR-10-ish in 7.62, and short carbines) are less about fashion and more about logistics, training, and modularity—things commanders have valued since at least the Napoleonic era. If you want sources, look at how post-1945 doctrine and procurement evolved (e.g., Chinn’s work on small arms, and broader doctrinal histories like van Creveld on logistics and combat systems).