[dsp1234]

React Native doesn't claim "code once, deploy everywhere", and in fact embraces native APIs where appropriate. As a reference, their slogan is "learn once, write anywhere". In other words, learn React Native, and write native apps wherever you want. Indeed one of the opening talks about React Native at React Conf specifically mentions that React Native is a leaky abstraction, and embraces that by allowing multiple escape hatches so that the native APIs are always available.

Railing against React Native seems like railing against Unity3d, or saying that abstracting the common parts of mobile development (while leaving the non-common parts 100% available) is a bad thing.

By the "right way" I mean use every language for its intended purpose, you can't build desktop apps in browsers

You can build desktop apps in browsers (ie emscripten). Additionally, can you explain why a "language" (as compared to platform specific APIs) has any relevance to what can or can't be built for a mobile device? For JavaScript specifically, if Apple didn't think that it was a language for building applications on iOS, then why would they ever have release JavascriptCore (which is what React Native uses)?