We had that (leading with the head) in the 90s as an old school training for o-line in Missouri. However at the time they had switched the good players on the l

We had that (leading with the head) in the 90s as an old school training for o-line in Missouri. However at the time they had switched the good players on the line to just using their hands as they had started allowing grabbing "inside the numbers". Still took a while for the transition to trickle down. All of the higher end camps and college camps taught using hands. Then I played in college, the people who hit with their heads on the line were hopelessly outclassed. We had a senior who was a physical monster but just loved using his shoulder/head to block, he never was put on the field (dude got a PHD in high energy lasers at the same time). It massively limits visibility and frankly, you can't HOLD with your head, which is, again, legal. Your hands are massively better. And the right amount of work in the weight-room you get your chest and triceps as big as most people's arms, you end up being able to double hit people. First hit is coming in with the arms and stopping their momentum by bending your arms. Second hit is that you can literally bench press them so you then shove them very quickly off balance or to the ground. Even when we did less than savory tactics, often out of desperation, like a leg whip (https://www.youtube.com/watch?v=RHdPcaRAkeg https://www.youtube.com/watch?v=RHdPcaRAkeg watch the running back in the first 5 seconds come in from the left) they taught us to have our heads up looking for the next person to block. The coaches we had in high school were not very smart and were doing it as a part time job based on what they remembered from high school. The coaches in college were professionals and did constant training and improvement.