Casey worked on tooling for AAA games that most certainly needed “that level” of optimization.

Jon Blow worked on numerous AAA games that required “that level” of optimization. And he’s one of the very few developers in the last 15 years who have managed to sell more than a million copies of a game running on a scratch built 3D engine.

You can disagree with their opinions, but they certainly have the experience to back those opinions up.