Why is it difficult for Asian teams to reach the World Cup?

A demonstration of true strength. The national teams of all continents in the World Cup, South America is a traditional strong team, Europe is getting stronger every year because of the development of the league, and Africa has always been a dark horse. Then Asia is basically the younger brother among the younger brothers in front of these three continents. If it weren't for the efforts of the Japanese and Korean national teams in recent years, so many teams in Asia 16 wouldn't have been able to get in. Although I hate to admit it, the future hope of Asian football should be in Japan and South Korea. Because their own league and national team goals and plans are on the right development path. As for ourselves? I won't type, so save my energy.