I'm actually a native developer. I'm responsible for a framework that supplies the react app with features it can't implement on it's own (or can't implement efficiently enough). So when I do builds, I need to know if I have any build warnings in my code, but it's almost impossible to see mine in the mass of React build warnings.

It also makes me wonder how compatible react apps will be, for example one build warning about a deprecated iOS feature I inherited actually causes a crash on iOS 12. We have over 400 warnings from the react code alone, how many of those are future land-mines? Quality development dictates your builds have few, if any, compiler warnings. Even if they are things you know will never be a problem you fix them or adjust your warnings so they don't potentially obscure other, more dangerous warnings.

That's a good rule for any professional development project, but when you are developing a shared class library for other developers to build professional products from, it's far more important. The React team's failure to clean warnings makes me question their actual ability and commitment.