It is a f*cking stupid rule that has absolutely nothing to add to the game, nor has any concept of that the game is about.
The whole concept of a try - historically - is to get the ball across the line so the attacking team could then "try" for a goal. The 'try' is followed by the conversion - and was given a points value to encourage free flowing footy.
The whole concept of the sport is to put two equal teams - 13 in attack, 13 in defence - and let them battle to score points. A player is taken off if their conduct is so contrary to the spirit of the game that they are not worthy to participate in it - hence the send off rule and later the sin bin. Not because some winger missed a tackle.
Fullbacks are probably the most important defenders in a side. The fullbacks we have are generally the best one on one defenders. They are least likely to make defensive lapses. So why penalise them if a winger misses a tackle, or gets outjumped from a bomb - or worse, a video ref ballsed up!
Imagine the same scenario in soccer after a goal. Do you take the goalie away and give the attacking side another go?
And if the original try was scored on the last tackle - where is the contest for posession or the turnover?
Any rule that contravenes the 6 tackle rule, the right for conversion, or the right of a player to participate if their conduct is worthy is a rule that decimates the very game itself.
The rule sounds like it was made up by a 13year old dickhead n an internet forum.