在Kotlin中，为什么抽象类不能像接口一样使用"by“关键字进行委托

interface MyInterface {
    fun doSomething()
}

class MyDelegate : MyInterface {
    override fun doSomething() {
        println("Doing something")
    }
}

abstract class MyBaseClass : MyInterface by MyDelegate()

class MyDerivedClass : MyBaseClass() {
    // 可以重写doSomething方法
    override fun doSomething() {
        println("Doing something else")
    }
}

abstract class MyBaseClass(private val delegate: MyInterface) : MyInterface by delegate

class MyDelegate : MyInterface {
    override fun doSomething() {
        println("Doing something")
    }
}

class MyDerivedClass(delegate: MyInterface) : MyBaseClass(delegate) {
    // 可以重写doSomething方法
    override fun doSomething() {
        println("Doing something else")
    }
}