Yes, artists can also utilize AI as a photoshop filter, and some artists have started using it to fill in backgrounds in drawings, etc. Inpainting can also be used to do unimportant textures for 3d models. But that doesn't mean that AI art is no threat to artists' livelihoods, especially for scenarios like "I need a dozen illustrations to go with these articles" where quality isn't so important to the commissioner that they are willing to spend an extra few hundred bucks instead of spending 15 minutes in midjourney or stable diffusion.
As long as these networks continue being trained on artists' work without permission or compensation, they will continue to improve in output quality and muscle the actual artists out of work.
Take for example video games. They distracted many people from movies, but also created a huge new field, hungry for talents. Or another one, quite a few genres calcified into distinctive boring styles over the years (see anything related to manga/anime as an example) simply because those styles require less mechanical work and are cheaper to produce. They could use a deep refresh. This tech will also lead to novel applications, created by those who embraced it and are willing to learn the increasingly complex toolset. That's what been happening the last several decades, which have seen several tech revolutions.
>As long as these networks continue being trained on artists' work
This misses the point. The real power of those things is not in the collection of styles baked into it. It's in the ability to learn new stuff. Finetuning and style transfer is what all the wizards do. Construct your own visual style by hand, make it produce more of that. And that's not just about static 2D images; neither do 2D illustrators represent all artists in the broad sense. Everyone who types "blah blah in the style of Ilya Kuvshinov" or is using img2img or whatever is just missing out, because the same stuff is going to be everywhere real soon.
This is like saying that photoshop is going to put all the artists out of work because one artist can now do the work of a team of people drawing by hand. So far these AIs are just tools. Tools help humans to produce more and the economy keeps chugging ever upwards.
There is no upper limit of how much art we need. Marvel movies and videogames will just keep looking better and better as our artists increase their capabilities using AI tools to assist them.
Daz3d didn't put modelers and artists out of work, and what Daz and iClone can do is way way more impressive(and useful in a professional setting) than AI Art.