It's a bit reductionist to say that it's just because they're 'snobs'....the way it was explained to me by my art teacher is thus:
There are artists, and there are artisans...artists create art, artisans create craft...the yardstick used [in the art world] to differentiate the two is the ability to reproduce the work given the same skills, equipment and environment.
Take for example, two metal workers...both with the same training, equipment, environment and requirements...likely it will be difficult to spot too much of a great difference in the resulting product. Same goes for photography...same camera, settings, direction, time of day, physical location etc...you end up with the same shot (as this article eludes to)....very difficult to tell the difference between two works of craft produced in the same way.
However....you take two draughtsman (sketch artist, not architectural)...with the same years of experience, give them the same pencil, same paper, same light, same subject.....you get vastly different results. Same for painting.
Interestingly, before Rodin, sculpture was considered a "craft"....he showed that it wasn't.
IMHO, the jury is still out on photography...with film it had an small element of art because of the nature of the development process...with digital, it's really hard to argue that it's not a craft.
The most telling point I think is that, if you talk to a artist (classically trained painter, sculptor or draughtsman) who is also a great photographer...he/she will usually not classify his photography as art, usually as craft....in fact, even the greats like Ansel Adams used to get angry when people called his work 'art'....he saw himself as an artisan and historian more than anything.
Classically trained artists sound like snobs sometimes because of the wholesale trivialization of their hard won skills....Donald Trump calls contract negotiation an 'art', I've heard some programmers call coding an 'art'...everyone calls what they do an 'art'....go spend 10 years trying to master classical portraiture and you'll see why those classifications are just laughable on all fronts.
But that's just the view of this programmer, classically trained portrait artist, sculptor and photographer :)