This is a principle in critique that is one of the primary ways of differentiating between reasonable and unreasonable critique.
It goes like this:

What this means is that you have the right to criticize anything that is present within a story, but if something isn’t present within a story, you do not have the right to criticize it. In this example, that would be the accuracy of goat herding. It should obviously be absurd to criticize the inaccuracy of the activity of goat herding if whatever you’re criticizing doesn’t have it at all: because it isn’t even there.

However, and this is very important to note: that doesn’t mean that you can’t criticize a story for lacking something. That is something you can criticize, it’s just a matter of not criticizing something for being depicted in a certain way without it being there.

Also keep in mind that the opposite is true too: if it’s present within a story, you have the right to criticize it.