In a monarchy all justice, authority, and moral order are centered on the person of the monarch, symbolically and legally.
In medieval and early modern English law, the “King’s peace” was the fundamental idea behind criminal justice. The Peace was not an abstract civic order; it was the personal peace of the Sovereign, extended to the realm.
The Crown was the earthly reflection of divine order. To offend that order — whether by sedition or obscenity — was symbolically akin to rebellion against the sovereign.
Pretty cool to think about how different that was, compared to today when people want the law to be based on maximizing the greatest good. What if this was banned simply because it offends the King?