Photography isn't art .. couldn't disagree with more on that score.
Camera, pencil, paint brush etc etc... they're just tools to create an image, are they not?
And throughout history artists of all media have been manipulating the final image be it paint or pixels. Colin Gifford images are extensively dodged and burned.
The skill to compose a good photograph is the same in as any other visual art ... photography; "painting with light" ... in fact photography would be a pretty dull pastime if the only images produced were "record shots"
We would then be robbed of stuff like this....(especially considering this guy first picked up a camera in 2009)
http://www.aaronyeomanphotography.co.uk/robin-and-taliesin-coombes-photography/
However, when it comes to the latest "fad" of adding smoke to model railway pictures I'm with you all the way - its just so naff it makes me cringe. Which isn't to say I don't like creative model railway photography but this looks like what it is - a white smudge.