I guess I'd like to say that reality is bigger than any image, and every image adds to it. Reality is (and the same as) anything we can take a picture of.
That said, here's big mythology here. Adams is a great example. Yes, him and his kit were there and took the Yosemite pictures, and folks have made a religion out of the Zone System and on an on, but his project fits in with a long tradition (Bierstadt) that had to do with portraying the American wilderness as a New Eden. In that context, Adams was a johnny come lately.
As a photographer, he was not so much interested in the decisive moment, a la Frank or Weegee (one of my faves) as he was in the transcendent moment: the earth that time forgot. But did you notice that there are no people in Adam's pictures?
That's a problem. Adams demands to be appreciated aesthetically at the expense of real people. There's the tension between the so-called "art photographer" and the photojournalist.
For me, as a landscape photographer, the landscape begins where I am. Adams might insist that it begins where you aren't. Photoshop seems to be a way to cross that divide.