Lots of these team sports require development leagues. And then decades of improvement.

I would imagine that their builds have something to do with it when it comes to certain sports, however, they excel tremendously in others. Baseball comes to mind with Japan being regarded as the #1 competitor each year in the world cup and Korea also being known as strong top 4 candidate. These could be outliers, but they present a case for Asian countries being able to compete on equal footing in team events.

That is a good point. Not to say that there isn't teamwork involved, but I would argue that baseball is slightly different in that there is a higher emphasis on individual skill than on teamwork. The better counter-argument would perhaps be the Chinese women's volleyball team that won Gold Medal in the Olympics (can't remember which Olympics, but they won it)