> What does that mean in practice though?

It means the idea isn't necessarily wholly impractical. That's not nothing.

I imagine superoptimisers scale extremely poorly, but that's a different question. I imagine they're best suited to bit-twiddling problems rather than, say, figuring out the best assembly code to implement a parallel Timsort.

I have to admit ignorance here though, I know almost nothing about superoptimisers.