> Rust just shifts the effort earlier in the development phase […]. You may spend a few hours struggling with the borrow checker.

And by the time you got it figured out, the requirements change, and you’re back to struggling with the borrow checker.

> that saves you countless days of debugging highly non-trivial defects, especially in a larger codebase.

Seems like many projects never get to the point where the architecture toil pays off. Instead, they spend 80–90% of their time trying to find the perfect architecture, which is then brittle against change.