Before states coalesced into states, which is roughly when they got legislatures, the role of the king was to be a barrier to the predations of oligarchs. Oligarchs were the landholding lords, who were always trying to conquer each other and oust the king. If the king was weak, the oligarchs abused the peasants ; if the king was strong, he had the support of the peasantry and could play the nobles against each other. The nobles gained the upper hand when they got permanent legislatures (more commonly called "diet" at the time). Previously, a diet only happened when the king called for it, which was rare. But with a permanent diet, being a busy body lawyer or representative became an industry. Its at this juncture where everything goes wrong. Legislatures... legislated. Regulation means to make things regular - uniformity. The innovations of legislatures are standing armies, conscription, public education and uniform curricula, central banks, lawfare, the eradication of local languages, and ever increasing taxation. Add any I missed... Nothing good comes from legislative bodies.
Absolute monarchies work much better for the people. Not better for the nobility, though. Democracy is oligarchy.