Euh, a simple logic. The Bellevue all-meat trial shows excess protein is impossible or with benign effects if at all, with some caveat specific to an all-meat diet (i.e. must eat enough fat, must be some fresh meat, etc). Conversely, kwashiorkor shows protein deficiency is possible and with severe and permanent effects. So, more protein is always better than less protein. And since RDA is a minimum to avoid deficiency but does not account for any unforseen situations that could require more protein, then more than RDA is always better than equal or less.