That's how most kids get into prestigious universities. Rarely, if ever, do kids just "stumble" into HYPS or Oxbridge, out of sheer intellectual power and luck.
If you want to get into those schools, you gotta know how to game works, and practice specifically for that match.
I went to a school like that, and the majority of my classmates were from upper-middle to upper class families that had poured money into their education since they were young, with the specific goal of getting them into top schools.
Yeah, that's unfortunately the thing, when you start throwing in a ton of different criteria / measurements. The people that know how the system works, will study to maximize those points.
My honest opinion is that you kinda of end up with smart people that are very good at test-taking, but may not be the best people when presented a set of problems with non-obvious solutions, or any guides or road maps on how to solve the problems.