If you want a spoilery TLDR:
It's more about the journey. He tracks down the origin, finds the support, finds the support flawed, and leaves you to your own conclusion rather than make a new flawed one.<p>The basic idea is that the origin assumes a highly critical inner hot loop, don't assume where it is, and optimize there.<p>There's some other time spent saying this justifies slower abstractions for maintainability elsewhere.