Those udder protectors have been used since Man first penned and domesticated the goat.
They twigged that the Kids suckled most of the milk and did not leave enough for their own use.
The protectors had a twofold use
a) It enabled the community to have nutritional milk
b) The Kids tended to forage earlier with their source of milk restricted. This lead to earlier maturity, hence more breeding hence more milk.
Pretty cluey folks, our ancestors...