" Agile, it seems like their real problem is with software development at scale, or really, any production process at scale."
I think it's more unique to software development. You don't see this kind of approach in large scale construction project with layers of contractors and subcontractors covering dozens of disciplines. You don't see this in car industry where they can do design, engineering, testing, factory tooling in 3 years.
I really believe the only reason why we do it in software is because we can.
And we can get away with it.
I also think the proliferation of outsourcing and offshoring was a strong catalyst for various reasons, though I'm sure that's a sensitive topic.
When industries that cannot get away with doing so tries, plane falls out of sky.
I think Agile can be great, but having been in the industry for 20 years and being put to practice, I see more reluctant Agile than true Agile. Meaning, people don't like it, but it has perception of working, so they go along with it, because there doesn't appear to be impetus to move away from it.