Ever since the helmet designs when to elaborate facemasks, and larger more protective helmets in general, the helmet has become a weapon instead of a protection.
When you go back even 30 years, there was far less use of the helmet in bringing guys down because of the injury it could cause to the tackler.
So, yeah, somehow the use of the helmet to tackle/knock down an opposing player needs to be stopped. It is too dangerous to both parties and it doesn't need to be.
Will it be difficult to enforce, especially at first? Yes. And I suspect the rule will, over time, be modified and nuanced.
