•Why it earns a slot
Why it earns a slot: it stages the same argument three times with escalating stakes, ending in Callicles' bald claim that might makes right, which makes it the clearest ancient text on why persuasion without truth is a weapon, not a virtue.
Socrates corners three defenders of rhetoric in a row, ending with a Macedonian house where the loser of the argument turns out to have the strongest stomach for it.
This distillation is written from the freely available original, which is always the better read when you have the time: Project Gutenberg.