The disappearance of the head-butt tackle

I see the French who have had some sad fatalities are going to test a single tackler rule. While there is no doubt the low/high tackle leads to some dangerous collisions, frequently of the 'no arms' variety, this seems to me a rule too far.....too hard to adjudicate in any case. And if you asked me to nominate the two most dangerous collisions in rugby, the double tackle wouldn't make the list. The clean out of fetchers would....necks dangerously exposed, tacklers pounding into fetchers seems like a real paralysis possibility. In the old days this bit of dangerous play was replaced with rucking, where a stud rash was the biggest risk. The most dangerous bit of play though was the head-butt tackle of Franks brothers fame. The tackler went in high and then thrust the top of his head into the face of the ball carrier. This horrible tackle, so much more viscous than a punch, has now effectively been removed from rugby by the new rules emphasis....and not a moment too soon.