For MJ in particular, knowing that they at least used to use Stable Diffusion under the hood, it would not surprise me if the majority of the secret sauce is actually a middle layer that processes the prompt and converts it to one that is better for working with SD. Prompting SD to get output at the MJ quality level takes significantly more tokens, lots of refinement, heavy tweaking of negative prompting, etc. Also a stack of embeddings and LoRAs, though I would place those more in the category of finetuning like you had mentioned.

I've also used it to generate art for deskmats I got printed at https://specterlabs.co/

For commercial stuff I still pay human artists.

I like them quite a bit, and you can get basically any size cut to fit your needs even if they don't directly offer it on the site.

Of course, art is so subjective none of this has any real meaning. MJ routinely blows my mind though and it is very rare something from SD does. The secret MJ sauce is obviously all the human feedback that has gone into the model at this point.

I think AI video will be a different story though. I think that is when comfyUI/SD will destroy MJ because MJ is simply not going to be able to have an economic model with the amount of compute needed.

For fine art MJ destroys everything and it is even close. I say this with using comfyUI/SD all the time.

But you do you and your anime porn.

In fact, anything that involves non-explicitly guided one-shot generation of anything with light/shadow/colors/perspective is entirely out of the question with the current crop, because all models are hallucinating hard and aren't controllable within a single generation. There are attempts at fixing the perspective without explicit guidance, but it's going to be a long way and it's not super relevant to how things are done anyway.

And for fine art, nothing beats a human painter, doing it by throwing prompts at AI mostly misses the point. I'm not even sure what you mean by fine art in this context, actually - surely not generating artsy-looking images from a prompt for fun?