Yes Im not familiar with the Chinese internet, however I've found that in expert topics, textbooks far outperform most internet content, with the sole exception of Wikipedia, which also sometimes has almost professional/academic-quality data on some topics.

I think existence of Wikipedia is a red herring, there's no historical inevitability that people will band together to curate a high-quality encyclopedia on every imaginable topic.

There might be similar, even broader/better efforts on the Chinese internet we (I) know nothing about.

It also might be that Chinese search engines are better than Google at finding high quality data.

But I reiterate - these search based LLMs kinda suck in the West, because Google kinda sucks. Every use of deep research usually ended up with the model citing the same crap articles and data you could find on Google manually, but whereas I could tell the data was no good, AI took it at face value.