What's wrong with committing in a broken state if you squash those into a working state before pushing?

Maybe nothing, I just don't work that way.

The beauty of git is that local commits don't get seen by anybody until you push. so you can commit early and commit often, since no one else is gonna see it, which gets you checkpoints before, during, and after you dive into making a big breaking change in the code. once you've got something you like, then you can edit, squash, and reorder the local commits and clean them up for consumption by the general public.

But to each their own!