Why do we need redux-thunk?

Question

redux

Why do we need redux-thunk?

I looked at a course on Redux, where an example of working with asynchronous code using thunk was given , but why is it needed if the same code can be described without it?

Here is an example with thunk:

//...

const asyncIncrementHandler = () => {
    return (dispatch) => {
        setTimeout(() => {
            dispatch({type: 'ASYNC_INCREMENT'})
        }, 5000);
    }
}

//...

<Button onClick={() => {
    dispatch(asyncIncrementHandler())
}}>ASYNC INCREMENT</Button>

//...

The same functionality, but without the thunk:

//...

const asyncIncrementHandler = (dispatch) => {
    setTimeout(() => {
        dispatch({type: 'ASYNC_INCREMENT'})
    }, 5000);
}

//...

<Button onClick={() => {
    asyncIncrementHandler(dispatch)
}}>ASYNC INCREMENT</Button>

//...

Why is this middleware needed, what is the use of it?