Rust requires discipline too. I can go around using Arc, Rc and .clone() everywhere without upsetting the borrow checker, I can use let mut a bunch and pretend if, match, etc. aren't expressions. This results in worse code, and Rust didn't stop me.
The borrow checker prevents a set of errors from being possible, but it doesn't prevent bad code from being written.
The borrow checker prevents a set of errors from being possible, but it doesn't prevent bad code from being written.