> Wouldn't a fresh look at things, essentially a "clean room" implementation offer the possibility of a novel approach to a thing or two, as opposed to making the same tool, just different?

Yes, sometimes, but if that’s what you’re going for it’s still important that you’re solving a problem that you understand well. So maybe I would be okay with someone with limited photoshop experience making an image editor, but I hope they still have a designer/artist/etc. background.