Similarly to #143, I'm getting "Unknown distribution option: 'use_scm_version'" and the setuptools_scm is not actually doing anything when setup according to Using the setup keyword (usage.md) and running python -m build. I think (and my tests confirm that) that the documentation should also mention that setup_requires=['setuptools_scm'] is needed next to the use_scm_version flag.

Another confusing thing (at least for me, as a newbie) is the info paragraph "Legacy simplified activation" that follows:

Previous versions had a "simplified" activation where listing setuptools_scm
in build-system.requires together with project.dynamic = ["version"] would
auto-enable version inference. This behavior was removed due to regressions and
ambiguous activation.

The new simplified activation using the [simple] extra provides the same
convenience but with explicit opt-in, making it clear when version inference
should be enabled.

Does it still describe something related to setup.py? If so, I just can't decipher what instructions it gives.