Central government wants to incentivize innovation and research so huge Chinese (and homogenized) population starts spamming patents and research papers. The system generates expertise for 1 good patent or paper out of 10. But volume is so high that 1/10 is enough to be globally competitive. Refine quality to 2/10 to reach parity. Refine to 3/10 and China becomes industrial leader. It's not hard to go from 1-3/10 in a short span of time when you have a massive labour force spamming its way into maturity. This is how China went from having poor academic research capacity into leading research many fields relatively fast if one looks past the "culture" / incidental inefficiencies and evaluate based on metrics controlled for quality. Supercharge this with industrial policy and state coordination to target strategic sectors.
It's the optimal development strategy that plays to PRC strengths - lots of people, somewhat competent ability to coordinate. In terms of fast, cheap, good, developing countries don't get to be good anyway, frequently poor governance = can't even focus on fast or cheap let alone both. Coordinating both = Deng model: poor China develops cheap and fast aka chabuduo. So Chinese population + spamming chabuduo + coordination = enough occasional, actually good outcomes to reach global competitiveness in ways that matter, fast. Though eventually need to reign in cheating and corruption via parallel improvements in coordination and culture to move onto next tier. Whatever you think of Xi, this is what he's been focusing on. Building premier institutions is also just hard and takes time to cultivate, especially if intellectuals previously purged, so need to spam out all the necessary components first anyway. Can't exactly have leading institutions without pool of experts first. The only place to cut corners for building institutions is to generate excess talent/components and assemble accordingly. Excess talent also necessary to mitigate brain drain (your amazing colleagues).
Elsewhere, Chabuduo manufacturing with Chinese population means plastic hangers to iPhones in 10 years. Chabuduo construction means enviable transportation systems, tier1 cities from fishing villages, and ghost cities that eventually gets filled by the hundreds of millions still waiting to be urbanized. Perfect/Good is the enemy of fast development.