It's component diffing, not DOM diffing. I agree that the later is unnecessary. omponent diffing is an implementation detail that enables the declarations that

It's component diffing, not DOM diffing. I agree that the later is unnecessary. omponent diffing is an implementation detail that enables the declarations that makes React worth using. Imagine a parent component that conditionally composes a Button that is either red or blue. You could track that button instance and flip the property if necessary. But that requires a lot of error prone boilerplate, as most real applications might have many states depending on many inputs. With React you just define which variant you want in the render function of the parent. No state transitions necessary. React then does the hard work of understanding that you rendered a red button then rendered a blue button, so it should reconcile the two.