The implicit assumption in the grandparent post is that it's good for society if the most gifted basketball players play in the NBA, the most attractive people act in the best movies, and the most talented engineers lead the top companies. Of course personal talent is a question of luck just as much as parental wealth - a meritocracy will not allocate the top places to those with the most worthy souls any more than a nepotocracy does - but more nepotistic societies are less efficient overall in a way that makes life worse for everyone there than more merit-based ones.