An important use for JSX preserve mode would be to leverage the React 19 optimizing compiler which auto-memoizes what otherwise would require useMemo , useCallback , and React.memo
by preserving jsx output, babel can fully trasform the generated .res.mjs files using the official babel react compiler plugin, which is compatible with vite
Event in case the React compiler works with rescript transformed JSX, would be just simpler to leave all the transformation to babel as would be part of the react compiler pipeline anyways