I feel like many of the more alternative teaching methodologies have unclear learning goals. What is "holistic problem-solving"? How can we measure it? Do we know that conventionally taught students lack it? Is it hard to acquire? Is it even important?

When I first went into the workplace, it took me a bit of time to adjust to the non-academic setting. You think differently, you work differently. I discovered and learned problem-solving skills that I was not taught in school. Frankly, though, I'm glad I was not taught those skills in school, because they are easy to learn in the workplace, especially if you have a solid theoretical grounding (something which is a lot harder to pick up on the job).

To the extent that generalized problem-solving is a real thing, I think it probably boils down to the ability to quickly internalize information and draw connections, which conventional schooling already focuses on anyway.

I think one claim is that the pile of rote memorized info is a required basis for novel solutions.

It seems to me that exam scores are a better metric of the underlying thing we care about, the ability to accomplish things in the world, than solution skill when faced with novel problems. Even if you're a very innovative person leading a project to do something entirely unprecedented, most of the tasks you need to do, text you need to read, etc. will not be novel.