[whywhywhywhy]

They don't really mean anything on desktop anymore seen as only a small minority of MacOS apps are built using those frameworks. Everything else is either Electron or custom cross platform UI frameworks like Adobe Suite, Alberton, Cinema4D etc.

[m_eiman]

The HIG is just as applicable if you use Electron, even it might take more work to follow the guidelines if you don't use the system-provided widgets.

That some choose to ignore the HIG and use the same GUI on multiple platforms is a problem, but it's not a problem that any guidelines can solve.