Case in point: you had hundreds of millions of JPEGs to vacuum up and bitmap image generation is amazing. But if you ask them to recreate the same scene as vector art, they will struggle to generate a decent SVG. Like, kindergarten-style pelicans on bicycles are the state of the art. It should generalize seamlessly, but somehow, doesn't?
I think it will happen, just like self-driving cars are happening, but it will probably be a slow process.