No, but it's not like all players skate with their heads down all the time, but it can happend for a second, and it's irresponsible to hit hard then, it will only lead to more concussions. And I doubt that very many players would use this as a strategy. But the feeling I get now is that all the players that hit constantly gets away while saying "well he kept his head down, it's his fault". Yes it's a contact sport, but it's also human beings that are being hit, I don't wanna see players have to retire early due to concussion. The players that hit needs to take more responsibility too. If someone gets a concussion it's went over the line, and I don't think it's ok to constantly blame the player with his head down, he didn't get hit because he had his head down, he got hit because the player who was hitting didn't care about it. And that could be seen as in intent to hurt, which is why these people should get suspended more often.
Btw, I've never seen any player that constantly skates with his head down.