Is this what Gatland is complaining about.....

Zone-blocking scheme The modern ZBS goes back to the Broncos of the 1990s. It was designed to counter the movement of defensive linemen pre-snap and the stacking of defenders, where there could be up to eight men near the line of scrimmage, with five or six offensive players assigned to block them. If you are a guard, and you are assigned to block the defensive tackle in front of you, then the defensive tackle moves pre-snap outside, what do you do? ZBS takes away the guess work, and, if everyone is on the same page, ensures the center and tackle on either side of you know exactly what you are doing, and how they should react to the change. The ZBS takes the offensive line and choreographs their movements. It no longer matters who is lining up in front of each offensive lineman. Instead, each lineman is responsible to block an area - of, if you will, a "zone." The ultimate goal is to double team defenders to ensure there is space for the running back. From there, one of the two blockers is then responsible to pull off the double team, and pick up a block on a linebacker. Gase likes to play with two tight ends on the field, not tipping his hand if it is a running play or a passing play. In the example of how a ZBS run (in this case an inside run, allowing for the running back to cut back to wherever the best gap forms) could look, we have two tight ends, with one responsible for the defensive end away from the run, and one responsible for the strong side linebacker - either blocking him or feinting a pass route to draw him out of the area. The tackles and guards then double team one defensive end and one defensive tackle, with the center then responsible for the other defensive tackle. From each of those double teams, depending on which way the defender tries to move, the offensive lineman on the side of the block then peels off to go block the other two linebackers. The running back should have a clean backfield, with options to hit any hole that appears.

 The running back should have a clean backfield with options to go at any hole that appears.....hahahaha....has the Gat nailed this one.

 Dr Moz it has been a clear nz tactic for a long time as has cleaning out players without the ball and those defenders behind the ruck. Gatland is pointing out the very obvious.

If the officials do not call these tactics as has been and is the case presently this type of play will continue.
Time to stand firm and deal with the issue (with the TMO if necessary) and a yellow card should be the call.