Raking?

having had my back & wherever else raked over the years in rugby; i really thought we may have seen the last of it (clearly) But i've just watched a filthy cheap shot rake by Albertus Buckl playing for Lyon against Sarries. Now in these days of safety first & concussion worries; we should not forget the sly filth that some players are apt to use. Gauging still goes on & so does fingering (of the nasal passage) lots of that has gone from the pro game but when the ref has seen the stamp & scrape; & proceeds to just give just a yellow card, then the game is in trouble. How can a stamp receive the same punishment as an arm across the shoulder?