Let me share my perspective about this matter, where football is considered as best sport and gives the opportunity to make money for a player then where more people will be interested in doing it. You said why India and China can't able to find 11 good players is because in India cricket is where money rains so every youngster from their childhood dream of becoming a cricketer than a football or javelin throw player but ofcourse India is also now focusing on improving their football participation by replicating something called ISL after the success of IPL (for cricket).
LOL.. I am from India and I have a fair idea about the situation here. Until very recently, there used to be provinces where football surpassed cricket in terms of popularity, such as Bengal, Kerala and Goa. But despite the large player pool and healthy demographics, India was never successful in football (unlike the case with cricket). Football needs good fitness levels and stamina, which is generally lacking with Indian players. Team bonding and co-ordination can also be important in football, and Indians are poor in that aspect as well.