>The Upper Palaeolithic cave art of Europe was a tradition that lasted for perhaps 20,000 years and it will always be rightly described as primitive. But it is upon those anonymous artists' shoulders — giants' shoulders — that later masters like Picasso were able to stand. The mercurial Spaniard himself declared: 'After Altamira, all is decadence.'
Sure, for maximum clarity, Neil Oliver could have written more like he talks. But this paragraph is clear enough and written in an appealing style. It might not be Paul Graham's favorite style, but that doesn't make it bad writing.
I also think the sentence he picked is particularly unconversational, which is misleading for two reasons. One, it makes Oliver's style sound more opaque and formal than it actually is. Two, even in a more conversational style than Oliver's, you're occasionally going to include something that's a step more formal.
I think Graham knows this, albeit unconsciously. Would he really say "Informal language is the athletic clothing of ideas" in a conversation? Probably not, but it reasonably passed his read aloud test because it's a good distillation of his point.
[0]: https://books.google.com/books?id=1Uk0AgAAQBAJ&printsec=fron...