There's different perspectives and trade offs.
It assumes that when _you_ make up a scale, the people that deserve to be at the top of it tend to be there. There's no reason for it to imply there's one universal scale of good people versus bad people.
For instance, if you want to understand why some people make more money than others (a trait that _is_ well-ordered, and can be put into a list), then somebody who believes in meritocracy would say that the people who make the most money earned it. If you want to understand why different people hold different positions in a company, then the meritocrist would say that between all the people who wanted each position, the person who was best for it tends to be the one that gets it.
Each of those scales may be more or less sympathetic to an explanation by way of meritocracy. But anyone who wants to make that argument doesn't have to construct an a priori global list of goodness for all people to give you an answer.
But what I am referring to with "nature vs. nurture" is that you can't separate them. Take away the physical basis of a person, all the DNA, and there would be no person. Put a newborn in a box, i.e. no nurture, a person would also not develop. So you can't assign a fraction to either one.
Similarly, there is no separating randomness from selection/merit, in my opinion, because the latter acts on the former and both pervade everyone's life.
That is what I mean by a false dichotomy. It's not just that life involves both randomness and selection, but that they are not opposed things.
Ok but I don't see why the just world fallacy is a false dichotomy. It is precisely a fallacy, because people don't acknowledge randomness and selection.
So it doesn't make any sense to me to say the world is just rather than unjust, or vice versa. Thus, I reject the dichotomy, as applied to the world. Something specific could be just or unjust, of course.