Comment by tlb

Yes, the entire field of software engineering ran aground on not being able to test how well people can write software.

But I'm more optimistic about testing programming models. You can run repeated tests, and compare median performance. You can run long tests, like hundreds of hours, while getting more than a few humans to complete half-day tests is a huge project. And you can do ablation testing, where you remove some feature of the environment or tools and see how much it helps/hurts.