I don’t think anyone claims that music or literature can’t be art (though some people claim that video games can’t) but in this context I’m using “art” as a shorthand for visual art of the sort that the public is interested in seeing computers create.

(Modern AI can also generate music and poetry, although it’s worse at those art forms than at visual art. Plus listening to bad music takes time in a way that clicking past bad art doesn’t and the general public does not care about poetry.)