I don't take the term as serious as the author of the book, nor do I have political ambitions to implement it. I think it was a rug that appealed to fairness. It was pretty ugly, but that is another story.

How the author formulates the critique is specifically not how it is understood by adherents from my experience. Not only for justice, imagine access for disabled people in public services like extra ramps or similar facilities which society provides. Do they have "merit" under natural law? Perhaps not. Does that mean adherents want to just ignore them? No, on the contrary. There are different a priori assumptions by people that like meritocracy and its critics.

What about social justice? Which metric do you use here to judge people. By frequency of occurrence by immutable characteristics? You can take both terms to mean the exact same thing. Doesn't mean you cannot have two groups endlessly fighting about who is correct about it.

It is not a political ideology. Maybe it is now, but that is more reactionary. But normally it would get some laughs if propped up that much.

What it certainly never meant is that you somehow need to earn your keep to receive justice and be treated fairly. But I understand the critique if it is conceived this way.

edit: We currently need to earn our keep in society for economic survival. I think working towards changing that is preferable.