Can anyone explain....

[ref2coach]

When the game was invented the ball used was a soccer ball. The inventor and the players were familiar with soccer rules. The "throw in" is described in soccer rules literature as "nothing more important than a way of getting the ball into play". The concept of "Team control" has little if no meaning in soccer rules. So by pure conjecture, that is how we, historically, have no "team control" during a throw-in.