The Panthers are in the process of creating a major issue for the NHL. The hit by Luostarinen in Game 3 was an example - it’s a team that plays incredibly dirty and is willing to take major penalties because they get away with it 80% of the time. And it absolutely affects the way other teams play, because you know you’re playing a team which has absolutely no regard for player safety.
The NHL has to worry that the blueprint for winning a Cup is going to to cheap shot and try to injure your opponent since you’ll get away with it most of the time, so the rare times it’s called the penalty isn’t sufficient to make it worth stopping.