When I looked I found that the top math talent in the world has been increasingly concentrated in the US (specifically MIT) over the last 30 years [1]. Staying in academia is an easy way for immigrants to stay in the US but it would be nice if there was an easier path out into industry.
It seemed like things began to change in the early nineties. I'm trying to track down who in the admissions office instigated it. I don't suppose you know?
At least when I was involved with math contests (early 2010s) it was more that there were a lot of ex-campers at MIT/Harvard, and that did a lot to convince me.
Po Shen did a lot to recruit students directly to CMU, but I'm not sure there was a similar direct line at MIT.
Some countries pull these kids out of school for an entire year to focus on training for it, while guaranteeing them entry into their nation's top university.
A lot of them become Fields medallists. From [1] "The conditional probability that an IMO gold medalist will become a Fields medalist is fifty times larger than the corresponding probability for a PhD graduate from a top 10 mathematics program."
[1] https://xquant.substack.com/p/where-have-the-international-m...