I really, really appreciate that you are allowing me the option of not particpating. I'm so relieved to know I have choices.
Reality is reality. The higher the resolution of the file, the truer the reproduction of the image is going to be. The flatter the lens field, the less lens distortion you are going to have.
Sure, anyone can shoot multiple shots of a piece of art and piece it together and make a print. The quality will not be as good as one taken with larger sensors, and flat field lenses. A 4x5 lens would allow you to have a larger "sweet spot" in the lens before the drop off of the lens starts to intrude into the image. A lens designed specifically for shooting flat art gives you even more usable lens area thus giving you more usable data.
I can shoot a 4x5 foot piece of art in 4 sections, run them thru a lighting equalizer software that evens up any light falloff at the edges and corners and then assemble those 4 sections and have a better final image than any amount of shooting with a DSLR would ever give.
..and if you are really interested in this process ..which I can assume you are because you posted it in the first place.. you need to know about the rest of the fine art reproduction world out there.
So, in the end, it all depends on how good you want your work to be. The best or just good enough.
Enjoy.