The reason is that there are three major sports events in the world.
Olympic Games, Men's Football World Cup, formula F 1.
The reason for the restriction is that the men's football World Cup and the Olympic Games are famous. If the Olympic Games also send a World Cup squad, it will actually reduce the weight of the World Cup champion (the world champion will be reduced from once every four years to once every two years)
In this way, the commercial value of the World Cup will be greatly reduced, which is unacceptable to FIFA.
After consultation, the two sides decided to adopt the age limit for the Olympic men's soccer team (under 23, three over-age players are allowed).