Conspiracies often can only target an individual or a small group; to conspire against a massive collective, to destroy a formidable power, simple scheming is insufficient.
Since the Sum Emperor ascended the throne, he had been plotting, constantly calculating against those Aristocratic Families, sowing discord among them. However, despite all the plotting, those families remained tightly knit, with none being outmaneuvered by him.
For Ancient Families like the Wang Family, without using physical extermination, they simply cannot be eradicated. Any policy suppressing the Aristocratic Families is just a minor annoyance to them; they not only can distort the Emperor's policies but can also use new policies to seek even more benefits for themselves.
The Sum Emperor had long seen through the tactics of the Aristocratic Families, and he was very clear in his mind that none of the measures were as effective as directly chopping off those people's heads.