The ruler of a nation holds supreme authority above all else.
Everyone can make mistakes, but the Monarch cannot. Anyone may be guilty, yet the Monarch cannot possibly be guilty.
Wielding the highest power, reigning supreme, how could one be at fault? Who dares to judge?
Even if one sins against the entire world, how could they possibly sin against the Monarch?
Throughout history, at any point, when a Monarch is convicted of a crime, it is always at a time when they have lost their power.
Those sanctimonious "decrees of self-blame" are hardly worth discussing. They are nothing but self-deception, a mere self-punishment of three drinks.
And the crime Yang Xuanji forces Yang Jiande to confess to this day is far from the trivial self-deprecation of "my virtue is insufficient."
