China dominated the Top500 list by 2017, with 202 machines compared to 143 from the U.S. Then the U.S. restricted Chinese access to Intel processors and other U.S. hardware in 2015, followed by broader export restrictions under the Trump administration in 2019, which have been tightened further by the Biden administration in 2022. As a result, Chinese participation in the Top500 list dwindled, to some degree because access of Chinese entities to the latest hardware got harder and to some degree because Chinese scientists no longer want to share details about their machines with anyone.
Why is anyone surprised that the country with the highest research output, that has historically dominated the Top500 list, has the fastest supercomputers?
People think the USA is some research mecca when it's just sending bombs to zios, restricting research to the rich, and extracting profits through state violence (eg. IP, colonialism, etc).
I’m a little more optimistic; like yeah, all of that is definitely happening, but there is lots of genuinely helpful research being done in the US. Not everything here is rotten. China’s research output is just an order of magnitude greater. See https://www.nature.com/nature-index/institution-outputs/generate/all/global/academic for a cool list of research outputs by institution.
Why is anyone surprised that the country [...] that has historically dominated the Top500 list, has the fastest supercomputers?
Because since then bans have been issued, specifically preventing the purchase of the "best" hardware, and that said country does not produce such hardware internally (e.g NVIDIA and AMD top of the line, and upstream with ASML). That's what why it is surprising, precisely because the situation has changed, cf e.g https://www.foreignaffairs.com/china/limits-china-chip-ban leading to possibly counter intuitive effects.
I imagine most people would like to better understand what hardware is being used, especially chips and to know where they come from, i.e
are they still somehow top of the line the country can't have through normal channels
somehow an order of magnitude of older chips they can legally purchase, so wasting quite a bit of energy but still similar results
the most unexpected using own hardware that is believed not to be available at scale
So yes it's arguably surprising because the situation is not as it was just a couple of years ago.