Surely traditional “open source” also needs some notion of a reproducible build toolchain, otherwise the source code itself is approximately useless.

Imagine if the source code was in a programming language of which the basic syntax and semantics were known to no one but the original developers.

Or more realistically, I think it’s a major problem if an open source project can only be built by an esoteric process that only the original developers have access to.

Source code in a vacuum is still valuable as a way to deal with missing/inaccurate documentation and diagnose faults and their causes.

Raw training datasets similarly has some value as you can analyze it for different characteristics to understand why the trained model is under/over-representing different concepts.

But yes real FOSS should be "open-build" and allow anyone to build a test-passing artifact from raw source material.