There is a ban on "heading" in soccer below a certain age. Isn't there? A quick search and it appears that the entire subject is mired in controversy, but the question isn't whether CTE is a real and dangerous thing. Rather, it's about mitigating risk, and determining at what age a child can be taught to head the ball. It looks like kids under 10 are not to be even introduced to heading, and above that, up to age 13, the "skill" should be introduced with soft balls. Some coaches prohibit their teams from heading, even if it is legal in the that particular league. My personal opinion is that kids should not, under any circumstances, be taught or allowed to head a fully inflated soccer ball. We know that there have been cases of kids being concussed by a fully inflated soccer ball, and we also know that repetitive brain injury is a source of many bad things as a person ages.
While blows to the head can occur in baseball, squash and other sports, blows to the head are not a "skill" being taught. It's an unintended consequence. The distinction may seem a fine one, but it's the line I personally think makes sense. In other words, are you teaching kids to deliver and/or receive blows to the head? Or are you teaching kids to play a game where a blow to the head may (or may not) ever occur?
Repetitive blows to the head are bad news. We know this. I have no idea why it's even an issue. By all means, teach the kids to kick a bag. But banning them in competition just seems like common sense to me.