"Conventional wisdom" is a way to sound really knowlegeable without really thinking. Why would anyone believe gun makers would deliberately choose to produce a commercial rifle that needed special ammo to function normally?
Factory rifles, including autos, get chambered with standard reamers. Standard dies size for standard chambers. Those who have installed custom barrels with tight chambers MIGHT need SB dies. Otherwise, standard chamber fit is usually sufficently sloppy that any chambering problems is probably due to incorrect use of standard dies.