And that's silly. A penalty is a penalty it should be called the same whether the first snap of the game or the last. Just like this is silly. Let them play in the regular season just like you are in the postseason.
It's not silly, it's human nature. We always push the envelope to see where the boundaries are. Not just in sports, but in everything we do. By calling it a little bit tighter in the regular season you are setting the boundaries of fair play. The players will respond by trying to go just as far as they are allowed without being flagged. Sometimes they go too far, but for the most part the boundaries are set and the players have been conditioned to where the boundaries are. That way when you get to the playoffs, you can lax the boundaries a bit and have fewer calls because the players have already been conditioned what to expect. That makes for a smoother, more enjoyeable game and yet still within the rules that have been setup.
Yeah, it's a little Pavlovian, but it's a fact, not fiction and it's not silly, it's actually quite fundamentally solid and it's taught to a lot of referee's in sports.
Another common place for this to happen is how balls and strikes are called in baseball games. A good home plate umpire will call the first couple innings tight, not giving the pitcher the outside of the plate, which forces them to not try to nibble too much on the corners, but once you have conditioned the pitcher to what is and isn't a strike, then you can call it straight up how you see it and the pitcher isn't expecting calls that you aren't going to give him and the batters have to be aggressive because the black might be a strike.
Basketball referees will do this too. Early in the game, everything is a foul. Later in the game, you let them play a bit.
You can't start out that way or it will become a brawl and people will get hurt.
You're not telling me you have never noticed this before?