In most of the same articles - American cannot be a meritocracy, social mobility isn't 100%! The assumption that a perfect meritocracy would be shown by your income having no correlation to your parents is about as opposite true as can get. If there is any heritability to ability/"merit", that will show up as correlation between parent and child incomes.

"Meritocracy" is a poor term regardless, because I have a different definition of "merit" than you do, and so do the authors. I've yet to see an article lamenting inequality that even attempts to define "merit"