The traditional critique of democracy is that it leads to what we moderns would call class warfare, demosclerosis, and political corruption (by political corruption, I mean the regulatory state, spawned by Olsonian multiplication of special interests). All of this stuff used to be called the social war, named after the Roman civil wars leading to Sulla's reforms.

To check theory against observation, compare Britain from the restoration to the mid nineteenth century, with Britain from the mid nineteenth century to the present.

Restoration Britain founded the scientific, technological, and industrial revolutions. British merchant adventurers went forth as mobile bandits, and settled down as stationary bandits, creating what was later called the British empire.

Democratic Britain has been downhill from there. If Cecil Rhodes or Lord Garnet was around, you can imagine what they would think of the present state of Britain.