Anyone who says the refs are not instructed by the league offices about calling penalties is naive. Look at the playoffs. For some reason in the playoffs, they let them play. Why is that? Because the league knows too many penalties called ruins the game. It creates the greater possibility that a game may turn on a penalty or may even decide the outcome. The league hates controversy like that so they let up on the flags. But this causes other problems, like when you see an obvious holding call on a TD run that isn't called, but then a DB swipes at a guy and hits his face mask and they call illegal use of hands. Or how do you miss a false start?
I saw the league explanation for the in the grasp call on the Dak sack. Its pure BS.
Personally, I prefer to just let them play as long as they do it consistently. If you are going to let an obvious penalty go then don't call the little stuff like that illegal use of hands on Byron Jones.
As to the question of weird calls against the Cowboys. Yes, the 12 men in the huddle a few years ago was total nonsense and they even changed the rule after that one. The illegal snap penalty this year and also the delay of game they called on Demarcus Lawrence when he shifted too quickly was total BS. For what its worth, the Cowboys are in the middle of the pack this year in penalties against them. They are near the top in the fewest penalties called against their opponents. At one point they were on top after 14 games in that category. I guess their opponents got called a lot in their last two games or some other teams had not penalties called against their opponents.