This is strictly for transforming JS. It has existed for over a year, here https://github.com/facebook/react-native/issues/8475 https://github.com/facebook/reac

This is strictly for transforming JS. It has existed for over a year, here https://github.com/facebook/react-native/issues/8475 https://github.com/facebook/react-native/issues/8475 as well. It's certainly possible that the babel team was never aware of it, but I'd imagine this has to do with the seemingly exponential growth of transformation time per source KB.