It is not + React. It's - React. It lists as one of its features, for example, a lack of a component lifecycle API (componentDidMount, componentWillMount, etc). This lifecycle API is one of React's best and most usable features. I can't give too much credit to a "tiny library" if it achieves its size by removing even the most basic features of other projects it's drawing from.
I don't mean to be dismissive of the work itself. Just sayin' - for people who might jump on this and think, "it's smaller, that's great!" - there is more to the story than its file size.