Taking checking out of hockey is like taking tackling out of football. When I started playing i did an instructional hockey team for two years. And was properly taught how to check. And what not. I understand protecting kids. But properly teaching them is the answer not just flat out removing it.
Impact is impact, and TBIs are especially bad news for a developing brain.
Your analogy to football is fundamentally incorrect. If tackling were to be removed from football, the game would no longer function. If hitting were removed from hockey, the sport would still function perfectly; it would just be less entertaining. See women's Olympic hockey for details.
So the other four Capital skaters cannot clear the zone, get back into position (to the point of colliding with each other), and stop the three Rags putting on a clinic... but it is Ovenchin's fault? Got it.
So Ovechkin is a professional hockey player, is the captain of his team, and has the largest contract in NHL history, but he cannot put forth the effort to play defense? Got it.