Why not just make the players wear dresses and have done with it?
If they haven’t banned boxers punching each other in the head as hard as they can, they are hardly going to ban footballers heading what is essentially an increasingly lighter bag of air.
The balls years ago weighed a ton, especially when wet, and had laces poking out.
The new ones are a different box of cheese.
Christ on a bike.
Actually, the old footballs were marginally
lighter than modern footballs when dry, they only became significantly heavier when wet. And obviously it only rained or snowed etc in a minority of games.
Anyhow, although the weight of the ball may well be a factor, injury is caused by the movement of the (soft) brain within the (hard) skull. Which is why eg rugby players often suffer concussion caused by jolting of the head during tackles, even when there has been no actual physical contact against the head. American football also has a serious problem with this, despite their players wearing helmets.
With (proper) football, it seems likely that with heading, even if the actual impact itself doesn't cause the problem, it may still lead to more frequent brain movement, and therefore greater risk, than if there were no heading allowed.
Which is not to say that heading should be banned from the game - like Boxing, imo it should continue on the basis of "informed consent".
But that in turn leads to two more issues.
First, just how "informed" are we? There is clear evidence to suggest that the relevant bodies, including the PFA

, have been dilatory in following this up with serious, concerted research.
Second, it is very possible that children are more at risk of concussion (brain damage) than adults, since the brain and cranium is not fully formed. It may be that when we know more, it will be decided that children should be banned from heading the ball until, say, reaching 16. After all, a child cannot be said to give his/her "consent" and parents may understandably be reluctant to expose their children to greater risk than they themselves undergo when playing.
Finally, Alan Shearer did a very interesting report on this subject last year, which suggested to me at least, that this is not a subject which should be lightly dismissed:
https://www.telegraph.co.uk/sport/2017/11/09/alan-shearer-fear-may-develop-dementia-years-heading-heavy-footballs/