I certainly think the next frontier for well-integrated PL tooling for QA beyond "inline unit tests" is "inline _parametric_ unit tests, with a standard interface to plug in greybox fuzzers and/or formal methods that are even more clairvoyant". programmers understand "writing assert()s in a test".

That’s actually helped clarify that for me, very concisely.

It makes sense, because optimisation is essential in some form for just about everything.

I’d say it follows then that a good abstraction hides the optimisation, and thus the complexity.