Well I think to define an artist, one would need to define art.
But art is a pretty subjective term, and often thrown around very frivolously these days.
One might consider a rusty nail through a Coke can a symbol of anti-capitalism, or even an artistic stand against processed foods in general, while another might just see a nail through a can.
Who is right and who is wrong?
Both, I'd say. Art is different things to different people, and we're not always going to agree. I wouldn't call someone who draws hentai or other cartoon porn an 'artist', no matter how well they can draw. But I would call a barely legible drawing of a road drawn by a man with cerebral palsy to represent the hard road he walks with his terrible illness art.
Some might agree with me, others might not.
I'd say it comes down to intent/message, as well as clarity in said message/intent.
But that's me.