Cladistics is nothing but a continuation of the old idea of eugenetics, transmitted from the pre-World War II to biological systematics in the 1970-ies by the German Nazi biologist Willi Hennig. The idea thus didn’t die with the end of World War II, but instead still thrives in biological systematics, eagerly waiting to show its ugly face again.
The fundamental error with this approach is the belief that kinds are real, called typology, or realism, as shown by Russell’s paradox. It means that the approach is fundamentally subjective, ie, can’t be objective, and thus that it can’t be a science, but instead is doomed to be a subjective pidgeon-holing of individual humans into made-up kinds.
The reason that this old idea never dies is that there are always some people that don’t understand Russell’s paradox, but instead believe that kinds are real. We can never explain to all people that kinds are something we make up to be able to discuss the world, and that there are many different but just as “correct” ways to make up kinds. Because of this, we have to head off the idea of eugenetics over and over again. It will continue to pop up in science, especially in disciplines that deal with systematics, and most especially in biological systematics.
So, watch biological systematics! It can bring you back to forced sterilization and concentration camps faster than you can find arguments against why. (That’s how cladistics took over biological systematics). Cladistics is a wolf in sheep’s clothing.