If we look at the performance of Asian teams against European teams, it is easy to understand that Asian teams are very weak. They are far behind. While teams like Korea and Japan have been able to improve themselves somewhat, they are still much weaker than European or American teams. The European leagues are very advanced. We don't see any better league in Asia than that. More time is needed to improve football in Asia.
I don't think that it has to do anything with time. Football is very popular in both Japan and South Korea, and this has been the case for the past decades. I am not exactly sure why the Asian teams underperform at international level. Despite their huge population, China and India almost never qualifies for the World Cup. Asian players are in general shorter compared to the Europeans, and that maybe the reason. But in that case Brazil and Argentina should not perform so well. I strongly suspect that there is some other reason.