Why were Enlightenment ideals never fully practiced by eighteenth-century rulers?

The Enlightenment ideals and philosophies of the major philosophers of the time period were in many ways ahead of their time. At the time of the Enlightenment governments were still dominated by monarchical or autocratic systems of government and the Enlightenment ideals of democracy, natural rights, equality, liberty, and others were not put into practice in many places until the end of the 18th century and into the 19th century as populations began to revolt and demand governments that embodied the values of the Enlightenment.