So I see where you're coming from. To first address Redux, etc, React has no opinion on state storage, it's a feature not a bug. Obviously you need to store state somewhere, and Redux, Relay, etc are just tools to address that concern. But that's really unrelated to what you're trying to address, which is coupling between leaves that have shallow common ancestors, but are themselves quite deep. Although in my experience a good website does group related pieces of information, and so well organized state often maps easily to a well organized UI, functional programming gives us the tools to avoid deeply nested expressions regardless of your application (or even your framework).

One thing to realize is that you always get to decide on the granularity of your compositions. It is not necessary to build a deep hierarchy if you design the granularity of your interfaces correctly. Another great tool is higher order functional programming, such as passing components to components (via children). In this way, it is easy to describe generic interfaces and supply specific pieces of data without having the intermediary interfaces know or care about that data. Another approach, akin to using something like the state monad, is to use Reacts context feature, but this is rarely needed, in my experience.

Personally I make heavy use of higher order components, and I find I rarely exceed a component tree height of three.