They really did a great job at math. The humanities were terrible, it was hopelessly politicized. But if you didn't want to deal with constant lectures about the struggles of the working classes, or constant coursework on marxism-leninism, you studied math or physics, or engineering. It helped, of course, that the government had as a national policy the promotion of STEM. But they did an amazing job at it, and produced a fantastic crop of world-changing talent.