"The first enemy of performance is multiple machines. The fewer machines that need to talk to perform a transaction, the quicker it is."

That is not strictly accurate. He's taking one aspect of performance - communication latency - and expanding that to be a universal truth of performance.

Pixar's render farms are good. Google data centers are good.

When you're CPU bound, more CPUs can make you faster. Note the specific use of the word "can," as in "sometimes."