A photograph given a watercolor look, oil painting look, or charcoal look through Photoshop is not a watercolor or an oil painting or a charcoal as it is not created through the use of the designated media (watercolors , oil paints, or charcoal). It may be a watercolor digigraph, or an oil digigraph, or a charcoal digigraph, but it is emphatically not an actual watercolor painting, oil painting, or charcoal drawing.
Some people do direct digital artwork using a tablet, and the effects available through the software. You have to be every bit as proficient (and have eye/had coordination) with this technique as you do using a brush, pencil, or air brush, pen, etc. In fact, in many ways it's harder because a brush, pencil, or pen has a certain friction "feel" between it and the artwork surface - where the stylus / tablet interface has the same surface friction whether you are using a large brush or small brush setting.
But, even if you do an original "watercolor" rendering through a computer it still never looks like a watercolor - it's really a different piece of artwork. Watercolors are especially difficult to emulate because you can work on wet or dry paper, wet over the top of applied paint, spot wet an area, etc. These effects really can't be duplicated through the computer process.
Likewise, an oil painting effect really never looks like an oil painting because oils (or acrylics) have a 3-D brush texture, and even greater texture if a pallette knife is used. Something you cannot reproduce with the strictly inkjet output.
But, all that being said, there is no reason that a piece created through a computer can't be art - is there?
As for photographs - a photograph is an image created through photography. Photography is recording an image on a light sensitive surface using a camera. Certainly, a DSLR meets that criteria. As for outputting through an inkjet printer, this is really no different than making a photo-lithograph or a photo-serigraph print, both of which have been accepted as art for many years.
Recently, I put together a panorama that I shot in 1992. I did five shots of the confluence of the Yellowstone and Missouri Rivers figuring that at some time in the future there would be a way to put them together into a single photo. I did that using Photoshop and another software program. It probably took me somewhere in the area of 20 hours to get the final image prior to printing. It was printed on my Epson 9600 and is everything, aesthetically speaking, that I had in mind.
Since creating it, I have sold two of them and had it accepted into a show. Is it art? You know, I really don't care. It is a gorgeous print that could not have been created without the combination of traditional photographic techniques and digital technology.
I guess I don't understand why people feel threatened by, or are constantly negative about, the use of digital technology - it has allowed me even greater freedom to produce images that I could not have done using only traditional photo processes.
Rather than being negative and bemoaning the "blurring" of lines - I'd suggest that carefully using the processes for creative purposes is a far more enriching endeavor.