It's a well-written article, and it certainly incites discussion. However, I don't believe photography has anything to answer for.
the question of what it must do to retain interest as art is once again freshly alive
I really don't think that photography has to justify itself any more than people who collect garden gnomes have to justify themselves. And I might be a bit murky as to whether six parallel blue pastel lines painted on a 1m x 2m bit of canvas is art, let alone worth hundreds of thousands of dollars. But I don't ask paintings or the galleries who purchase them to justify themselves either.
Also I don't think an excess of photography devalues all photography any more than an excess of soccer players somehow devalues the game of soccer. Cream rises to the top, and dslrusers is one forum that showcases that.
Finally as to the opnion
One of the most common answers had nothing to do with art. It was a conviction that photography's great purpose was to record historical truth.
Well, that's one opinion. But you might as well argue that Words somehow cause problems because they can be used for fact AND fiction AND to sell things AND to insult people AND to deliberately mislead. Quite simply, yes words can be used to do all these things. Photography is no different.
Finally, I think all great art is infused with opinion (possibly even six pastel parallel lines painted on canvas). If a photograph leaves you cold then the 'artist' may well have misfired.
I could keep writing, but I'll stop here