If you 'screened' in a football game you would be penalised for obstruction.
I can't think of any other sports where you are allowed to obstruct the way you are in polo.
OBSTRUCTION (technically known as “impeding the progress of an opponent”) can only occur if the ball is not within 'playing distance' (ball is generally 1-2 yards from the player).
Pulling an opponent's shirt is a foul in football. But if you watch any corner in any professional game, you will see that all the players on both sides take hold of each other's shirts. This is hardly ever penalised.
Also, the kind of obstruction in football that you are referring to is where a player pushes the ball past an opponent, and the opponent moves to block the player's path to the ball.
This would be a foul in polo, or at least, I would call it as a foul.
Pulling an opponent's shirt is a foul in football. But if you watch any corner in any professional game, you will see that all the players on both sides take hold of each other's shirts. This is hardly ever penalised.
Also, the kind of obstruction in football that you are referring to is where a player pushes the ball past an opponent, and the opponent moves to block the player's path to the ball.
This would be a foul in polo, or at least, I would call it as a foul.