That's what I was saying. The actual `setState()` function can be called with new references from immutable data, the same references that already existed but

That's what I was saying. The actual `setState()` function can be called with new references from immutable data, the same references that already existed but were mutated, or even no references at all if you mutated. So, literally, `setState()` does not care what process you used to potentially update data before calling it - it just applies a shallow merge of whatever object you passed in to the existing `this.state` object, and then queues a re-render. It's the _rest_ of your code that might care. The primary reasons to actually update data immutably before calling `setState` are for easy and consistent implementation of `shouldComponentUpdate` / use of `PureComponent`, and general FP principles that immutability should be preferred over mutation.