There's still a difference between commented code because it is dead and bitrot and code-in-progress. I am among the first people to delete commented code and send anyone looking for it to git tutorials, but I've also kept git branches short by keeping code behind if flags (that are false in builds/production) while working on it so that I can still give that code the benefit of other refactors or compile errors and so that other developers are aware of that partially complete code.

It's not a dichotomy, it's an orthogonal spectrum. Of course it is hugely useful to be good at source control. Of course it is still sometimes useful to have code compiling in CI/CD that "isn't ready yet" but prone to cross-fire in other on going work and refactoring. (Plus source control is greatly useful for answering "Why is this flag false right now? Who was last working on it and for what project?" and keeping that code honest that it isn't just bit rot.)