Because then it wouldn't be React. React tries to solve the conceptual spaghetti created by heavily evented systems, by putting everything into one stream of notifications so that you can immediately know where things are being changed and by what. It prefers synchronous over asynchronous for this reason also.
Sorry, what?
Are you saying basically that event subscriptions are all declared in some declarative language, making them all easy to find "in one place"?
