I firmly believe that training models qualifies as fair use. I think it falls under research, and is used to push the scientific community forward.
I also firmly believe that commercializing models built on top of copyrighted works (which all works start off as) does not qualify as fair use (or at least shouldn't) and that commercializing models build on copyrighted material is nothing more than license laundering. Companies that commercialize copyrighted work in this manner should be paying for a license to train with the data, or should stick to using the licenses that the content was released under.
I don't think your example is valid either. The reason that AI models are generating content similar to other people's work is because those models were explicitly trained to do that. That is literally what they are and how they work. That is very different than people having similar styles.
I also firmly believe that commercializing models built on top of copyrighted works (which all works start off as) does not qualify as fair use (or at least shouldn't) and that commercializing models build on copyrighted material is nothing more than license laundering. Companies that commercialize copyrighted work in this manner should be paying for a license to train with the data, or should stick to using the licenses that the content was released under.
I don't think your example is valid either. The reason that AI models are generating content similar to other people's work is because those models were explicitly trained to do that. That is literally what they are and how they work. That is very different than people having similar styles.