It also becomes more pronounced when teams sizes are smaller at younger years. 7v7 teams where only the top coach goes to the A team. You loose good coaching and also the opportunity to play against better competition if you are younger in comparison to peers. It creates a large headstart and advantage to those closest to whatever cut off date is used.RAE is strongest u10 and below.
For the highest levels it tends to taper off by u12.
The problem is (if you think RAE exists) the results of RAE are already baked in by u12. It might not be happening as much at the highest levels. But the players that have been chosen to play for the best teams have already benefited.