I'm an artist myself, absolutely love Midjourney, and have absolutely no problem with it being trained on any and all art -- just like human artists have been doing for millenia.
Long term, if Adobe is clearly worse than the competition as a result of being legally/ethically conservative they will lose users. They will get a lot of likes on twitter but companies will not pay for a firefly subscription if it's worse than Stable Diffusion.
I'm an artist myself, absolutely love Midjourney, and have absolutely no problem with it being trained on any and all art -- just like human artists have been doing for millenia.