I'm not prone to hysteria - and it's a fair criticism that the OP was badly titled and not especially well written - but the nub of the post is correct; it's a despicable strategy with potentially devastating consequences, and it needs to be stamped out of the game; and Brian Mac had it right way back when - make it illegal to join a tackle below the knees after contact, and it's gone, just like that.
I've watched the Wigan match back on replay, and it was definitely more notable than most games; it was, I suspect, an attempt to control the really big forwards who have been wreaking havoc, but it was done recklessly and without due care for player welfare - which has been, as evidenced by Shaun Wane's ranting exhortations to his players to "be fu**ing reckless!" a Wigan tactic for some time.
I hope that the one on Fifita is properly handled by the disciplinary panel, to send a strong message; and that the attention its getting on social media will have a more far-reaching impact. We need this out of the game once and for all, and some coaches have more to do than others.