This is the fault of capitalism, under which you are required to sell your time and skills for cash to survive. Under this system, no one who isn’t independently wealthy can be an artist without commoditizing their art. So that’s the lens through which people view art: just another commodity to sell so one can survive, not unlike grains or oil. The quote also shows that the artist is fungible in this conception, only the output matters no matter how it got there, as long as you can sell it.