Should they ... not prepare? What are you even suggesting? Do you seriously think it's so easy to just communicate the complexities of a business without having practiced hundreds of times? Have you even tried? I get the feeling you're just an armchair philosopher who doesn't have any idea what the heck you're actually talking about. Either that or you're just being a dick. It's complete nonsense.

By doing flash cards, they were able to accomplish the exact goal you stated much quicker and more effectively than blundering their way through the YC interview and trying again in 6 months after they've had real pitches. Or should everyone just be as amazing as you are and be able to communicate these things without ample practice? Ridiculous.

So I guess people should stop preparing for Google interviews by looking at and practicing the myriad of coding puzzles they've previously asked. You'd be stupid not to.

It sounds like after studying with the flash cards they were able to do just that.