const TodoView = ({title, isFinished, onClick}) => (
        <li>
            <input
                type="checkbox"
                checked={isFinished}
                onClick={onClick}
            />{title}
        </li>
      )

    const TodoViewContainer = observer({todo} => (
        <TodoView
          title={todo.title}
          isFinished={todo.finished}
          onClick={() => todo.finished = !todo.finished}
        />
      ))

Mobx allows you to be as pragmatic or dogmatic as you choose to be