That is not what the rule has been "all along," because the standard for completing the process was changed in 2015.
2014
Item 1: Player Going to the Ground.
If a player goes to the ground in the act of catching a pass (with or without contact by an opponent), he must maintain control of the ball throughout the process of contacting the ground.
2015
Item 1. Player Going to the Ground.
A player is considered to be going to the ground if he does not remain upright long enough to demonstrate that he is clearly a runner. If a player goes to the ground in the act of catching a pass (with or without contact by an opponent), he must maintain control of the ball until after his initial contact with the ground
The point is that it hasn't been officiated consistently, under either standard. Officials are obligated to go by the rules in place at the time.