I was following [this tutorial](https://youtu.be/Ke90Tje7VS0?t=4218), And on 1:10:18 (timestep included in link) he wrote `this.setState({ count: this.state.count + 1 });` *(where count is a primitive value inside state object, that is then displayed on page after button click)* From tutors words i understood that we need to specify `count:` inside setState so that React will update this value in state object. But i noticed that i can just write some bullshit in setState like: 

```
  handleIncrement = key => {
    this.state.totalCount += 1;
    this.state.tags[key] += 1;
    this.setState({ countBlabla: 23213123 });
  };

```

And HTML still will be updated correctly, without re-rendering everything. (I've checked in developer tools, only values that were changed are updated, everything else is untouched)

I have also tried: `this.setState({});` works good. But `this.setState();` does not.

So what's the point of passing setState a parameter?