Those example images are of really low quality video. Usually people who care about image quality do not care about that. Can you show some ~720p 5mb/s x264 versus 3-4mb/s VP9 samples?
Low resolution samples are the norm, I think it's because low resolution makes it so you can see how the compression algorithm works. If you a high resolution comparison, you would need to zoom in to see the difference anyway. There are, of course, compression artifacts that are readily apparent even in high-resolution (chain link fences, transparent wipes, etc) but I suspect that they are in the minority.