First, meritocracy segregates talent rather than dispersing it. By plucking the highest achievers from all over the country and encouraging them to cluster together in the same few cities, it robs localities of their potential leaders — so that instead of an Eastern establishment negotiating with overlapping groups of regional elites (or with working-class or ethnic leaders), you have a mass upper class segregated from demoralized peripheries.
Second, the meritocratic elite inevitably tends back toward aristocracy, because any definition of “merit” you choose will be easier for the children of these self-segregated meritocrats to achieve.
But even as it restratifies society, the meritocratic order also insists that everything its high-achievers have is justly earned. “He was born on third base and thought he hit a triple,” Ann Richards famously quipped of George H.W. Bush; well, the typical meritocrat is born on third base, hustles home, and gets praised as if he just hit a grand slam.