History has yet to produce a “good” monarch (i.e. one that yields better results than the alternative, which is liberal democracy).

better is doing an insane amount of lifting here. In the last 30 years China has lifted more of its own people out of poverty than all democracies summed together over the same time period.

Crucially, the way in which China has achieved this has been through economic liberalization.

The rest of China’s potential will never be unlocked as long as it is kept artificially constrained by the political control of authoritarianism.

What?? History has produced a huge amount of good monarchs. There are some around even today, for example Oman.

There is no reason to believe that Oman wouldn’t do much better as a free, democratic country.