诛九族，是吓阻背叛、树立威信最有效的方法，没有之一
被满门抄斩的恐惧，甚至能用写作为家族族曲，用以威吓敌人并警惕自己
例如冰与火之歌中的 Lannister 族曲：The Rains of Castamere
曲： http://youtu.be/-FF2fBRKxtk 词：
And who are you, the proud lord said, that I must bow so low?
Only a cat of a different coat, that's all the truth I know.
In a coat of gold or a coat of red, a lion still has claws,
And mine are long and sharp, my lord, as long and sharp as yours.
And so he spoke, and so he spoke, that lord of Castamere,
But now the rains weep o'er his hall, with no one there to hear.
Yes now the rains weep o'er his hall, and not a soul to hear.
指的就是当 Reyne家 被 Lannister家 在斗争中击败时
整个家族都被处决，最后一个被行刑的人
只能感叹家族城堡只剩空荡的大厅已无人可吊念
吓阻背叛者的效果十足，也能时时提醒全家人只许成功不许失败
所以株九族当然有用，只是现代人大家都怕变鲁蛇，所以废除了这种制度了