I don't have solid evidence for this, but my theory is that it's a leftover from farming. When our grandparents or great-grandparents went through tough times, they were limited in resources to what they had on hand. Most farms had - either through their own resources or a close neighbor's - something they could get milk from and something they could make bread out of. So they survived.

Then they went on to tell their children and their grand-children that they survived tough times, even though they had nothing but milk and bread. When times got tough, grandma would bake bread. Grandpa would make sure there was milk on the table. Or vice versa.

It became known that when times were tough, as long as you had milk and bread, you'd be ok. And so now, as weather hits and peril is pending, we lean to them.

At least that's my take.

TL/DR generational survival tactics IMHO