Football helmets also used to be really heavy and hard.
In my time, we were unaware of the negative effects, so we used our helmets as a weapon.
This was normal. It worked.
For example, if you are a running back with sufficient mass, come in low with high speed and manage to place your helmet on the helmet of the defender (who is often moving laterally) you could literally knock them out.
During kick off, you could have two players running into each other full speed from 50 yards out. Of course the person who is willing to go fully into contact will win. The person going for a Rugby style tackle might land on his behind.
The force of such impacts was immense. I have had my metal face shield broken out of the helmet.
I have seen broken jaws from the impact, people getting knocked out, having concussions.
I am horrified about the things they let us do in the 90‘s. Even in practice, these contact drills that were designed to take away your fear of contact, teach you to use your body as a weapon.
I just hope it is different today, but if I have kids, they will not play Football