It's been a super long time since I looked at this (decades), but at least when I did a lot of reading on it, this kind of recommendation is based on making sur

It's been a super long time since I looked at this (decades), but at least when I did a lot of reading on it, this kind of recommendation is based on making sure you have protein availability in the bloodstream when it is being taken up for muscle building. It's not so much the amount as the timing. Again, at least at the time when I was reading about this stuff, there were lots of recommendations for having 5-7 meals a day, or splitting your carb and protein intake (for example eating your protein 1 hour after eating your carbs in order to take advantage of the insulin rush). There are dangers corresponding too much protein intake -- calcium depletion, for example. It's also pretty hard on your kidneys. A lot of advice in the gym is not necessarily geared towards health as much as it is to maximise muscle development/protection. I will also say that nutrition research is chock full of poor science and worse explanations of that science by well meaning popular books. It was my hobby when I was at university (hence decades ago) to look up the actual papers referenced by popular sports nutrition theorists and never once did I find that it held up (either the papers they were referencing were horrible studies, or they got the conclusions completely wrong). It's been a long time since I've had access to a good library, so I've completely lost touch, but I suspect that little has changed. I do wonder about some sports teams and whether or not they are puzzling things out. For example, the Sky cycling team is famous for their "marginal gains" approach -- trying to get a tenth of a percentage of improvement from anywhere. But I haven't found them to be particularly forthcoming about nutrition, for example.