John Muir's "strength-giving" food

In a 1918 National Geographic article entitled, "The Acorn, A Possibly Neglected Source Of Food," author C. Hart Merriam writes:

"John Muir, during his arduous tramps in the mountains of California, often carried the hard, dry acorn bread of the Indians and deemed it the most compact and strength-giving food he had ever used."

I take slight issue with the headline of Hart's article. Acorns are "possibly" a neglected source of food? Acorns are extremely high in food value, can produce huge volumes of food with zero soil disturbance and minimal inputs of fossil fuels, literally drop to the ground every fall by the bazillions of tons, and have a genetic diversity and elasticity which would easily lend itself to breeding improvements that could increase yields exponentially. And yet we don't eat them, and eat annual grains instead.

I'd say that there's no "possibly" about acorns being neglected as a food source!