>the prayer beads seem uncannily real [...] Van Eyck must have spent days to stare at them (shortened)
Of course not. By the time he painted that, he was an accomplished painter. Therefore, he knew already (formally or not) to look at specular highlights, reflected lights, how the shadow works, etc. At some point, you could reduce all of the observation to light interacting with material. But like you do with math, you have a reduced number of special cases for which you can remember the result without deriving each individual steps.
>It’s longer than a normal human neck!
It's a kind of weird fetishization of "master artists". Any mistake they can make is an incredible deliberate choice. The people who say that generally would not be able to distinguish a 'master painting' from other paintings from the same era by 'minor artists'. They can only everything through the prism of what their art history book tell them they should think. Why is the perspective wrong on the scallop shell, what is the statement for the sea looking like a wallpaper? Did Botticelli never see the sea before painting it?
Then going to Van Gogh. There is no consistent theory that makes a Boticelli "good" and both Van Gogh paintings "good". They obey entirely different concepts of what "art" is supposed to be.
The part about explaining how to build up concepts in programming seems way more interesting, but it seems to me that it would be much be without the analogy with art that is built upon layers of misunderstanding. To me this is exactly the kind of mental burden that I had to painfully unlearn before I could start improving in the ways of art, and reconstruct a mental model of how things actually work.