Idiomatic design would be a big one; there are a lot of ways to design a program in a higher-level OO language that, if followed in C, will lead to a program with lots of bugs around error handling and resource cleanup.

This kind of ties into the argument made by some in the Rust community that "the ownership was there the whole time" -- in a language without automatic memory management, you really do need to be aware of the life-cycle of an object in memory. Rust's specific rules aren't fundamental, but "even when an error occurs, I know what cleans up this object / this state" is.