> I recently finished a contract at a (very large game dev) company where some tools were written in Rust. The tools were a re-write of python scripts and added no new functionality but were slightly faster in Rust. > The reality was that these tools were unmaintainable by the rest of the company. Only the author "knew" Rust and it was hard to justify a new hire Rust developer to maintain this small set of tools.

I can believe this, but it's funny because I work on a project where the main product is written in Rust, and it's the build tools written in Python that are the technical debt that nobody really wants to touch! In our case I suspect rewriting them in Rust will end up being the right thing to do (if/when we can justify the switching costs).