Actually research shows that most concussions to the defender happen when they go high. The World Rugby research into concussion found that when a tackler goes high, they increase their risk of concussion. This situation also was the highest risk of concussion in the game. The researchers took their findings to a panel of players and coaches so they could create laws to reduce this risk. Hence the new high tackle framework. It is as much for reducing risk to the tackler as well as the tackled player.