If you pay attention to all the corgi examples, the sofa texture changes in each of them, and it synthesizes shadows in the right orientation - that's what it's trained to do. The first one actually does give you the impression of weight. And if you look at "A bowl of soup that looks like a monster knitted out of wool" the bowl is clearly weighing down. I bet if the picture had a more fluffy sofa you would indeed see the corgi making an indent on it, as it will have learned that from its training set.
Of course there will be limits to how much you can edit, but then nothing stops you from pulling that into Photoshop for extra fine adjustments of your own. This is far from a 'cool trick' and many of those images would take hours for a human to reproduce, especially with complex textures like the Teddy Bear ones. And note how they also have consistent specular reflections in all the glass materials.