That’s a ‘Chicken or Egg’ argument. He’s taught and performed all the time because a great many people in every generation feel that he’s the best writer in the language (and some would say in any language). But he is to English what Homer is to Greek, Virgil to Latin, Dante to Italian, Goethe to German, Pushkin to Russian...
Not really. We all know the bandwagon is a powerful tool for making things popular. There’s a reason CBS finds a way to declare all of their shows #1 at something for their advertising, they know there’s that crowd that doesn’t want to miss the boat. The myth of Shakespeare perpetuates the myth of Shakespeare, as long as he is held up as the pinnacle the world will support the idea that he’s the pinnacle.
Funny that you led off your list with Homer since there’s a good chance that there was no such guy but actually a bardic tradition that built the myth of the man. A myth which now perpetuates itself in the same way.