If you are speaking at a conference or conveying information in an oral presentation, you usually use minimal text and prefer graphics in visual aids because you don't want to engage the linguistic processing parts of the brain on two separate tracks (the verbal content of the oral presentation and the text content of the visual presentation) simultaneously.
This isn't because text is an inferior medium on its own -- which it isn't -- but because its inferior as a simultaneously complement to an oral presentation.
This is clearly false, and makes me think you didn't read the article, since the article provides a counterexample right near the beginning; try to express this in an image: "Human rights are moral principles or norms that describe certain standards of human behaviour, and are regularly protected as legal rights in national and international law."
Of course nobody's proposing we abandon images; they're indispensable for many things, like the conference slides you mention. But if I had to do a presentation and was forced to choose between only text and only non-text images, I think the best choice would be clear.
A far better one is, "Human rights are political conditions necessary of the life of a morally autonomous being." Tyranny and democracy are both "political conditions", as is "the rule of law" and various other things. One useful thing about this definition is that under it rights are both natural and inalienable: a right may be violated (a condition may not be met) but the necessity of certain political conditions for moral beings to be able to make their own moral choices (moral autonomy) cannot be removed.
So not only does text enable us to present ideas more succinctly and precisely than images, it allows us to argue about them effectively, and to have those arguments remain somewhat accessible for thousands of years. Images can be used as components of an argument (I've never published a scientific paper without graphs) but without the accompanying text the argument is woefully incomplete, whereas text alone is capable of sustaining a vast range of arguments without any accompanying images.
I had a professor that used Powerpoints with nothing but photos to accompany his lecture. His lectures are the ones I remember the most.