In short, because the rules matter less and less as the playoffs progress. By the end most rules are optional.
Not a fan of that and never will be.
not as much optional as subject to interpretation and let the players play.
still not as lax as the games played in the 80's. I watched a 1978 rangers vs flyers game and good lord nothing was called, including someone getting hooked around the neck and hauled down because he got the shot away anyway.