Yet.
I don't know if it will always stay this way, though. If one day I read a novel and I think, this is a great novel. I appreciated it, I felt myself growing from it. And then later I learn it was written by an AI. That's it, that will prove that great AI novels are possible. I will know it when I see it. I haven't seen it yet, but if it happens, I'll know.
So it's really just a technical question. Not a philosophical one.
He in essence claims there is some intangible attribute of a work that defines it as art or not depending on both the person who made it and the process they went through.
It does seem like a slightly romantic notion, since for any given item you can’t know if it’s art or not just by looking at it, which seems a bit odd. But then again, I suppose there’s a reason people pay for guided tours at museums so they can learn about the history and background of a work.
Side note: the title is editorialised; it should be “The Hidden Cost of AI Art: Brandon Sanderson's Keynote”