I've been thinking about this for a long time now. Offense has been plummeting again and many subtle hooks and holds and interference infractions go ignored (in some cases, not so subtle).
I used to complain about this type of thing being incompetence of the refs or inconsistency, but I actually think it is one purpose now. True, there still is a lot of inconsistency between games, which is extremely frustrating, but in general, I'm confident that the refs aren't being asked to call it by the book like they were 10 years ago. Power plays are likely around 50% of what they were back then....which on one hand is good....I hate all offense coming off PPs, but it's only good if the reason is because there are no infractions. You now get left with stars not being about to shine as bright as they can because lesser skilled players are able to hold them back by interfering.
I honestly believe the league made a call here to allow stuff to go uncalled to slow down the play again a bit in the hopes of limiting the head injuries that they have largely blamed on the speed of the game. Concussions are down, but is it because of this or is it because players are getting it and knowing they can't target the head? Probably a bit of both, but I do detest all the non calls that have been seemingly getting more and more.