I think Tony expressed it well in the above post.
Russ makes the case that exploring the human condition is, for him, perhaps the most noble and suitable pursuit of photography. It is within this genre that he sees images that are meaningful in a way that landscapes and other genres of photography are not. Along the way, he posits reasons for why the camera is perhaps "a lesser medium", because of its limitations (at least that is what I read/interpreted).
For me, exploring the human condition is one of the important pursuits of ANY medium. I would argue that photography is at least as successful a medium for this genre and, for our generation, perhaps it has superseded more traditional art media. But I also find other genres of art, and other goals of art no less valuable. A landscape which is soothing, peaceful, tranquil, is just as important (perhaps more so for me) as one that is stirring.
I don't qualify art or meaning by its medium. So, for me, a photograph, in any genre, is not intrinsically lesser or less successful than other forms of art. That photography can be a powerful medium for exploring the human condition (HCB, Eugene Smith, Lange, others), I wholeheartedly agree.
Anyway, this is the "coffee corner". To me, Russ's essay is like the start of a conversation we might have over a coffee after seeing an Ansel Adams or W. Eugene Smith exhibit together. The Internet has given us the opportunity to have a "coffee and conversation" that would be impossible any other way. I have no interest in being right or proving others wrong. I enjoy the debate, learn things, and perhaps give others something new or different to consider.
Indeed, but my original response to the OP was to quote that telling line about camera function within the wider scope of the medium.
As several folks instantly leaped in contradicting, and saying that of course photography can be creative (which was not denied either by Russ or moi), it appeared clear to me - still does - that the point was being mistaken for something nobody had claimed, until they did that themselves.
As for the question, what's photography for? then the answer is rather wide, and the best one can do is reply from a personal persepective, devoid of preaching or suppositions. So here we go.
For me, photography was an interest that began when I was very young. It grew in tandem with a love for art, especially the later schools of Impressionism and Post-Impressionism. I would visit galleries whenever I could, and a cousin and I used to blow pocket money buying postcards there, and trying to paint the same things ourselves. He went on to art school and spent/is still spending a lifetime as a professional, fine art painter. I realised I'd never make it because the native talent was far too thin, and as bad, art education had been precluded due to school attitudes that relegated art class attendance to the "lesser student", so the alternative co-existing love of photography grew to replace the other one. The school had never even considered photography could be a career... all fine intentions, but so misplaced.
So I started with love of it, then followed up living the career, and now, retired, I'm still doing it when I can muster up the drive. But what's it for, is the question. It is a means to an end, a way of fulfilling what artistic/creative urge one might have when the more noble arts are beyond one. It's a way of making money - sometimes a helluva lot of it - and a way of starving slowly without really being aware of the fact. It's a way of spending your day in the more pleasant company of pretty girls instead of with some sadistic, miserable old sod in a glass office, the door of which you better knock before entering. It's a way of keeping one's sorry ass off the production line, of avoiding an early death from the industrial smog of a machine room full of turning- and grinding-fluid vapour and the noise levels that turn you deaf too soon.
It's a fine way of seeing the world at a level only a client's deep pockets would allow. It's for providing the space to stop, relax, breath some air and spend pretty much 24/24 with your wife if you want to do that - which I did, which is why I married.
In short, it's for living a life that makes one happy, even if the other rewards may or may not ever materialise.
What it may represent for other people I can only guess. But that's their job to state, not mine to attempt to state on their behalf.