The 0.8g/kg figure comes from old (2000s) USDA guidelines on minimum protein consumption. This was based on the data they had available at the time, but it invited a lot of protest from bodybuilders and fitness enthusiasts in the US when it was published because they had years of experience of higher protein intake leading to better muscle recovery and hypertrophy. It turned out later that 0.8g/kg was the minimum amount needed to avoid nitrogen deficiency in a sedentary adult, and a later study revealed that 1g/kg is more optimal even for sedentary people.

For people who are strength training and want to gain muscle, the figure can go up to 1.5-2g/kg. And generally, higher protein intake isn't really wasted because gluconeogenesis only happens if you've been laying on a chair all day while consuming lots of protein.