It fits some kind of apps. I've built one React Native app where the "lowest-common-denominator" was more than good enough (no special code for different platforms) and would have worked just as well as a web app but wasn't possible due to the nature of React/React Native. If I would have used ReactXP I could have published it on the web as well and used just one React code base so this is good news for me.

I don't understand what you're trying to argue about. If you don't like it, don't use it.