These seem to be made by artists trained on traditional drawing. All drawings show knowledge of cross-hatching or pointillism, correct use of values, perspective, and so on. That’s why it looks great today, these qualities are independent of how advanced the digital medium of the time was.
Look at this one for example - my mind is blown:
https://blog.decryption.net.au/images/macpaint/lesson3d.pngHow do you even do that? Zoomed out it looks like a nearly photorealistic street scene, zoomed in I just see seemingly meaningless patterns of black and white. Magic. Unbelievable.
This image in particular made me wonder if there was some type of tracing aid involved. Maybe the dutch-looking street reminded me of Vermeer's method. I wonder what input device they were using? I was using a pretty nice input surface for doing CAD work sometime around 1990-93 on a PC, and we had occasion to lay transparencies on top and trace on them. I don't know if Macs 5 years before that had this type of peripheral. And anyway, there were certainly some special artists I knew of back then who could do this with a mouse and enough time.