It looks like react-cursor is 1300 loc [1], mobservable is 1900 [2]. How is that "vastly less code"?
1 - https://github.com/dustingetz/react-cursor/blob/master/dist/... 2 - https://github.com/mweststrate/mobservable/blob/master/dist/...
1 - https://github.com/dustingetz/react-cursor/blob/master/dist/... 2 - https://github.com/mweststrate/mobservable/blob/master/dist/...