And when the state has relevance to two components? Now it's okay to make it a global, because we can't be bothered to type "prop = value"?

I'm just not buying this argument. People add Redux to projects because they intend to use it, and there's almost never a case where a piece of data is actually needed in enough places that it should be global. It's certainly not common enough to justify importing a whole framework for managing global state.