That only works on people who aren't shameless and are willing to reevaluate their own behavior based on external criticism. Sometimes you have to pick your battles.

So back to my question: "What would shaming them for this accomplish? Is the idea to shame them so much that they pretend to like ugly people like me? What would be the point of that?"

What effect on their behavior do you hope to accomplish by shaming pretty people for not wanting to hang out with ugly people? I'm not seeing a productive reason to do this.