I think it is very fair to argue against the idea that there are perfect meritocracies. But... there are few perfect anythings? To what end does that argument go?
Put differently, the dream of a meritocracy is far more appealing as an ideal than the vast majority of ideas that have been competed with it.
To directly address the rhetoric of the article. The concern at the end of "It will be no small task to right this ship, and to refit it to more closely resemble the vessel of opportunity we aspire to." But, the entire point of the success of the US system is that we do, in fact, have the best chance at getting to this ideal over anyone else. And we have had our best successes not be replacing older ways, but by incorporating them into what we try next.
We more closely resemble that aspiration today than we ever have in the past. And yet we have far more calls for ceasing our progress in the name of past mistakes than ever in our past, too. This could be fine, as we also have far more capability today than ever in the past. But it is tiresome to hear wave after wave of why the successes we have, are somehow not actually successes at all.
Meritocracy fantasy seems to play a large role in libertarian dogma.