Why would you want a refactor into a broken state?

You always need to figure out how much you're going to bite off with each refactor. It's usually possible to do things incrementally.

I don’t think that’s what the parent was saying.

There are cases when refactoring Rust code where it’s possible to hit limits in the compiler related to e.g. lifetime inference. When these limits are hit, simple straightforward refactorings that are perfectly safe become more complicated - suddenly you’re forced to manually annotate lifetimes, and to thread those lifetimes through function calls, and…

And your small, incremental refactor suddenly isn’t. It doesn’t happen all that often, and they’re working to reduce how often users run into these challenges, but a number of cases like this still exist. And when you run into them it can be a frustrating experience.

You might want to test some optimization or refactor without crossing all the Ts. Lost of reasons you'd want to quickly iterate without doing the maximum amount of work needed upfront.