By this standard, no one could ever say anything about "China" at all. Sam Altman says that the Chinese economy passed the U.S. Was that the Uighur economy? Tibetan economy? Subsistence farming economy? City-dwelling economy?

See how these questions add nothing to the conversation?

If the conversation is about China collectively, then it's not invalid to make other statements about China collectively. If you disagree with the parent's assertions about China, then let's hear it, but just pointing out that China is really big does not tell us anything we don't already know.

You're eliding two very dissimilar things. I'm not saying you can't group people and say quantitative things about them (like GDP). That would be stupid.

I'm saying I have no idea what a statement like "the Chinese value hard work" means. It is not testable or quantifiable, and it's genuinely meaningless. Now maybe you could publish some survey data that shows Chinese people more value hard work. That might add something to the conversation.

Why is something overly broad stereotyping?

People don't treat populations and individuals as the same thing; the population is its own entity with its unique properties, and, obviously differences. The question is whether those differences are sufficiently exploitable. This is how policy works. If you are saying that you can't generalize over a population, you're saying that there are roughly zero between-population differences that are exploitable for strategic policy. Random things are unstrategizable.

I think that the Chinese and Japanese value hard work more than Americans and Canadians, and I think so because Americans and Canadians have an unfortunately true belief that intelligence is highly predictive of performance, and also that intelligence is not meaningfully improvable. On the other hand, I think that Chinese and Japanese people have the belief that effort is a far better explanation to performance.

The problem is that performance must surely be at least a combination of effort and ability; a depressed person may have the bodily ability to pick up the phone for their friends, but they might not care anymore.

I thus say this: if you go looking for studies on cross-cultural pedagogy, I claim that you're going to find that American and Canadian students are significantly more likely than Chinese and Japanese students to avoid harder challenges, to pursue easier challenges, to practice mastered over unmastered material, and to avoid a problem after poor marks. Does this speak to all work? Of course not. But it's a window into culture, rather than just comparing mean hours studied or worked between populations.

China is quite homogenous ethnically, 90+% Han! You can of course generalize and stereotype, you'll just have many more chances of being wrong.

Indeed. People forget that China has twice the population of United States and European Union combined. It's often silly to treat them all as one uniform group.

I once had a friend say something about how the Chinese valued hard work. Then I asked him what cultures don't value hard work. He squirmed as he started ticking off a list of countries whose populations are predominantly black/Latino...

Hence the need to separate the concepts of culture and race, rather than using them interchangeably the way we do now.

A group's uniformity has nothing to do with its size.

You're bind-minded