You can just insert the word "some" as required.

Agreed, but the headline wouldn't travel nearly as well, if at all.

> Why some Americans are switching to soy

Would be more accurate than

> Why Americans are switching to soy

But wouldn't garner nearly the same amount of clicks.

There is conscious exaggeration in omitting 'some' - a fluff-blog click-farm trope I don't enjoy seeing in the developer space.