Because of the sugar shortages and shift in production that sent the chocolate to the troops?
I believe that was the reason. I just remember as a small kid in rural England - right after the war - the GI’s would hand out candy to us.
When chocolate was removed from rationing - it was still in short supply - my siblings and I lined up at the ‘sweet shop’ just to get one bar of Cadburys and we had to share it. It was several years later that I had my first banana!!!!
Makes one appreciate the bounty we have in US grocery stores today.