Oh, and Rust tends to do this for performance problems rather than I-need-new-features.

"I was using ____, and having performance problems. I coded up a quick replacement in Rust to start the process of tuning it for better performance...and...it was already 5x faster than the original...and I forgot to use a release build. And it solved a persistent bug we'd had."

Rust isn't the best for fast prototyping. It gains ground once you want to move from prototype-quality to production-quality-for-something-important.