The browser does do this already to an extent. The difference is that React constrains the operations a user can do (i.e. we only give them the DOM node if the

The browser does do this already to an extent. The difference is that React constrains the operations a user can do (i.e. we only give them the DOM node if they explicitly ask for it and only let them manipulate it at certain times) so we eliminate the operations that cause the DOM to be slow. If the DOM were to implement this it'd have to break backwards compatibility.