In recent weeks, two leaders – Xi Jinping in China and Mohammed bin Salman in Saudi Arabia – have consolidated personal power to degrees unprecedented in their countries' recent histories. And Donald Trump, presumptive leader of the free world, has praised them both for doing it.

In late October, China's Communist Party added what it called "Xi Jinping Thought for the New Era of Socialism With Chinese Special Characteristics" to the constitution. A cult-of-personality campaign for Xi, reminiscent of the days of Mao Zedong, is in full swing. So are purges of his political rivals, dressed up as "anti-corruption" drives.