IMO, everyone misses the forest for the trees as far as what's going on with the reffing.
The reason they chose not make some calls where McDavid and other star players are concerned is they have a weird mandate, spoken or unspoken, to police the parity in every game. They don't want to let one player draw like 4 calls a game because that would favor one team.
Every once in a while they'll get a new mandate from the league to focus on one specific thing (obstruction, slashing, goalie interference) and they'll go crazy on that for like 2 months before everything just reverts to the mean. But as long as they have the freedom to put their whistles away one day, call everything the next, do make-up calls and dictate the temp. of each game, this is going to stay a problem. It's not about some kind of axe their grinding.
And the league can't do that much about it as long as ex-refs are put in charge of officiating and the NHLOA successfully negotiates for referee freedom (the reason they review some of their own calls on ipads is because the OA didn't want refs to lose their say to the war room).