[seanhunter]

Perhaps the hand is an example of something for which you really need an actual model of the anatomy to draw convincingly whereas lots of other things (eg faces) a very simple proximity model will generate just fine. Since a diffusion model doesn't have an actual conceptual model of the things it generates (it literaly just learns to remove noise from training images and then eventually "removes the noise" from a totally random bitstream until it generates your image).

It's interesting that lots of artists practise sketching using wooden models of a hand that they can pose in different ways.[1]

[1] This type of thing can be found in most art shops https://www.quickdrawsupplies.com/product/8-20cm-artists-pos...