Complete view of protein, human health, exercise, and aging. RDA vs higher-protein intake, and high-SPC
Protein synthesis & its role in hypertrophy is, first of all, not the be-all, end-all of higher protein intake benefits.
So neither 1.6 nor 2.0g/kg/day represents a hard stop with no additional benefits from a higher protein intake. The reason why some people can claim that 1.6 is all that’s needed depends on how complete you want the conversation to be. But, when they make that claim, they are always, and only, talking about healthy, younger omnivores, and they are only looking at protein synthesis and hypertrophy. Seemingly doing so because they are convinced that human health, nutrition, and fitness never, ever go beyond these two things, and that everyone happens to be young, and an omnivore.
This is based on an incomplete understanding, or at least a limited perspective, on food, health, aging, and fitness.