Chinese education is also extremely constrained by the practice of "teaching to the test" to the point that the Gaokao indirectly stands in the way of innovation and reform in education. Schools doing interesting things to improve the quality of education are historically not very competitive on the Gaokao anyway (e.g., some unusual rural schools where students historically have bad prospects anyway and parents are overburdened or indifferent) or explicitly trying to carve something out outside the college track (e.g., private tech/entrepreneurship schools created by big tech companies).
There may be some good things about the Gaokao but having spoken to some (Chinese) teachers in China, it's also a limiting factor for education prior to university in a lot of ways, limiting the freedom of teachers and driving up risk aversion in parents.
(It's also effectively graded on a regional curve, which might be a good thing but isn't meritocratic in the straightforward way you suggest.)
So what are aspects of being well educated not reflected in the Gaokao? How could those aspects be assessed as objectively and unbiased as possible?
Or (some) western education is too unconstrained and have strayed from purpose.
Scope of gaokao = teaching the test is just teaching everything a well rounded student should know. it's not sats where you can cram a few test tactic sessions and get a few 100 extra points. At the end of the day, gaokao is there to beat knowledge floor/foundation into kids, and one would argue knowledge floor is very deep if you want to generate most bodies that can transition into technical tertiary. Like... if one want human capita pool to be launchpad for innovation, you don't make calculus optional to athletics or other extra curricular.
IMO useful perspective is PRC diaspora, who readily acknowledges they don't want their kids going through gaokao not because it's ineffective but because it's tough, and half the reason they immigrate is because their statistically mediocre kids can't hack it under gaokao, but with some east asian education rigour/pressure will still be top 5% students under western education.
There are those who argue that the entire high school curriculum in the USA is formed and molded by College Board changes to the SAT (and similarly to the ACT).
It makes sense, if the SAT starts asking you do calculate epicycles, schools are going to add Ptolemy to the study, or look worse than those that did.