Btw, there's a reasonable argument to be made that constraints are what drives creativity. From my own experience, East Germany had much better political jokes than West Germany. Mostly because you didn't need a carefully worded joke in the West, you could just open a newspaper.
Compare also https://en.wikipedia.org/wiki/Oulipo and http://d7.drunkenboat.com/db8/oulipo/feature-oulipo/para/oux...
(Just to be clear: I vastly prefer to live in a free society.)
As for the parent comment, I think he's alluding that pre-modern Japanese art and culture had a lot more overlap with pre-modern China's, which makes it somewhat less notable from a Chinese perspective (e.g. something like England vs Australia; different, but there's overlap).
But post WWII we see a massive divergence in cultural export and exchange (e.g. England or Australia vs the US). South Korea is another example (I've actually seen Japanese entertainment consortiums lamenting at the perception that the S. Korean entertainment industry seemed to be better funded and more able to export their culture). Just looking at Chinese history, the golden age of creativity and inventions seemed to occur when there were more freedoms (which I would argue is pretty much any era prior to the PRC since their control is unprecedented in conjunction with modern technology). Granted it was the olden times, so there were more things to be discovered, but it seemed like China back in the day was on a roll (off the top of my head, movable type, paper, matcha, bonsai, porcelain, celadon, silk, gunpowder)
I agree constraints can generate creativity, but
is there evidence that constraints generate more of it?
I think the strong general consensus is that the right kind of constraints can indeed foster innovation - think of the constraints imposed by, say, early video game consoles. Or forms of music that grew from various constraints - the energetic DIY ethos of punk, or how hiphop thrived within the constraints of working with turntables and early electronic tool vs. live instruments.
Of course, the kinds of constraints matter. I think you're talking about societal constraints. I would guess that they generally have a much more negative effect on creativity.
You seem to be throwing together all of pre-PRC China into one big blender?
There have been lots of different dynasties and long stretches when China was not unified. Many of these dynasties were more different from each other, than some dynasties might be from the PRC 'dynasty'.
Tossing all the achievements of thousands of years into one bin, and comparing them to what has been produced in the last few decades also seems a bit off.
Most (or all?) of the examples of inventions you describe predate the Qing dynasty.
The last emperors before the republic and later the communists were off the Qing dynasty.
China was perhaps at its biggest sophistication compared to the rest of the world during the precocious Song dynasty. See eg https://en.wikipedia.org/wiki/Song_dynasty#Economy
Song China was arguably the first 'modern' country in the world. Where 'modern' is used in the historian's sense of the world. https://en.wikipedia.org/wiki/Human_history#Modern_history
there's a reasonable argument to be made that constraints
are what drives creativity