Because his artwork wasn't really that good. his depth of field, shading, and consistency are all subpar, which is most evident in the second picture. the windows suggest mismatched floor heights and they slant upwards towards the right of the picture. His shadows are all the same with one wall being dark, a 45 degree slant on the other and the roofs being illuminated regardless of lighting. In the first picture, some people are drawn with distinguished outfits, while others in the same position on the z-axis are just blobs, but people farther in are distinguished again. Also that dude in the third picture is walking around with a dislocated shoulder. I mean if he practiced a bit more maybe he could have gotten somewhere, but he should have taken his rejection as a sign to better himself and not to commit mass genocide?