SWC is written in rust, and Babel is written in javascript, so you've proven the OP's point. Vite can be configured to use SWC.

The recent conversation was about Vercel benchmarking a tuned Turbopack+SWC vs. a default Vite+Babel, not really an apples to apples comparison. When Vite is configured to use SWC as a compiler, Vite's HMR gets faster; but it's not the default for compatibility reasons.