Why are key and refs needed in this code?

Question

React

Actually, the question is in the title. Why are key and refs needed in CommentList? And are they needed, like, and without them everything works. Full code on github link

class Article extends Component {
    
    static propTypes = {
        text: PropTypes.string,
        date: PropTypes.string
    };

state = {
    updateIndex: 0
}
    handleDelete = () => {
        const {deleteArticle, article} = this.props
        deleteArticle(article.id);
}

    render(){
        return(
            <div className='article card' style={cardStyle}>
                <p>{this.props.text}</p>
                <p>{this.props.date}</p>
                <span style={btnDelete} onClick={this.handleDelete}>X</span>
                <CommentList article={this.props.article} ref = {this.setCommentsRef} key = {this.state.updateIndex}/>
        </div>
        )
    }

 setCommentsRef = ref => {
        this.comments = ref
    }
}

Answer 1

Key is not used in the CommentList component, so this is an extra props.
ref -> this.comments is also only available in the Article scope but it is not used there, so these 2 props are superfluous.