JavaScript原型和调用

我将在push方法上添加一个额外的更新功能,代码如下:

function update() {
    console.log("update");
}
let method = 'push';
let oldMethod = Array.prototype[method];
Array.prototype[method] = function () {
    update();
    oldMethod.call(this,...arguments);
}

Can someone explain why I should use oldMethod.call(this,...arguments) rather than oldMethod() only?