This starts well before the national team — and it’s more than just the over-recruiting of height (although that has a good chunk to do with it)
The Chinese Basketball Association still has the institutional attitudes that have powered it through the last thirty years — more practice is good practice. Drills and repetition is the only way to get good at something. If you notice, Chen Jianhua was the only player to ever make it to the national team without going through the sports schools to junior teams to national teams level — he won an open entry Nike grassroots tournament — and despite his injuries and attitude issues, he was by far the most creative player that has ever suited up for China.
It’s the junior hockey in Canada problem illustrated in Malcolm Gladwell’s outliers book writ large. The tall kids get the access to facilities and coaching and paths to further development — the short, fast, clever, quick kids end up playing halfcourt 4 on 4 in their local parks.