One of the issues is that the technical properties of a photograph can be measured. If it can be measured, it can be compared with other measurements. That makes discussing...ok arguing... about a photograph easier.
I can measure focus, tonal patterns, the physics of composition, lighting, exposure...... The list goes on
If I can measure it, I can re-create it using technology and technique. My ability to use the technology and implement my technique can thereby be
discussed argued.
This is why
discussions arguments about techniques and technology are common on the Internets Tubes forums. It is easy to understand and it is easy to cherry pick facts that support one's opinion and refute someone else's opinion.
What I can't measure is art. Because art does not have a definition.. or to be more accurate, art does not have a universally agreed upon definition. Every one has their own definition of what is and ain't art.
This is why I can't say that something is good or bad art or even if it is or ain't art. I can say that I personally like or don't like this form of art. I can also say that this particular example of art adheres to or differs from some "arbitrary standard". But that does not indicate whether someone's art is good or bad or whether it is or is not even art.
Therefore any
discussion argument about art can quickly devolve into a matter of opinions. Naturally anyone's opinion that differs from *my* opinion, must be wrong, uneducated, or is unsophisticated. After all, if they were, they would naturally share *my* opinion.
Photographers like to proclaim that it is not the equipment but the photographer, but if you notice most of the postings on photographic forums involves equipment. It is not the equipment but I will sure argue about minutia about lens parameters to my dying breath!!
Why?
Because
discussing arguing about technology is easier than
discussing arguing about artistic intent.
Something is art if and only if the person that created it, considers it art. Whether anyone else considers it art is their opinion. But the artist is not constrained by anyone's opinion but theirs.