When I was a child, I would pick buckets full of acorns for a local type of zoo.
I was always disappointed to see the hogs go to town on the old, dark, rotten acorns instead of my clean, green, fresh ones.
It was only later when I got into survival skills that I realized, why they would do this.
Also: I am not an acorn connocieur, but I think there are quite some differences between the varieties.
Like you mention in the op: We lost some knowledge there. People back in the day knew these things.