Plato is fantastic for exposing people to critical thinking. All his dialogues are relatively short compared to shit like Hegel or Deleuze or even Aristotle. The form of said dialogues are just that, dialogues, so those who are exposed to constant television and movies and other simulacra media can understand the flow and structure of the writing. The content itself is less important. Plato is baby's first philosophy and newbie gains. It's a rapid pace of examining the world in a way outside of the norm. Most of them never go anywhere because >OH SOCRATES I MUST LEAVE TO PARTICIPATE IN THE VOTE TO KILL YOU RIGHT NOW AFTER YOU UTTERLY DESTROYED ME IN DEBATE<SOH-KRATES U R SO WIZE!
Even with that taken into consideration, the content of his ideas do subsequently create the building blocks for future philosophers, and as the guy quoting Deleuze in the other thread said>the power and authority of philosophy comes from it's history.