I think the author is using a much narrower definition of "meritocracy" than many people might. There's a difference between thinking that people who occupy some position of responsibility are "the best" and thinking that in general that they instead simply meet some basic bar of competence. The problem is that for many roles, you can't simply hire somebody off the street and expect them to perform acceptably. I can write software for you but I am in no way qualified to be your lawyer.

Figuring out who is the best is hard. But making sure people are capable of doing a job before we hire them (or promote them, or whatever) is at least a tractable problem. I have a big concern that people who are advocating that we "abandon meritocracy" are going to make it really hard to have any standards at all. This might be fine for hiring people to work behind the counter at McDonald's but it's not going to work if you're trying to assemble a team to find a cure for an infectious disease or, I don't know, design the first Global Positioning System, or you know, any number of things that allow us to live in a modern society.