It's not about copying their style, the main difference is AI companies making revenue training their systems on other people's work, while the original artists are not being compensated for helping train their systems.
Engineers figured out how to scrape sites, decode and filter tags, classify images, and feed them into the training dataset.
All the original artist did was publish an image online to be seen by other people.
It'd be like Google compensating people for putting things online that the search engine links to.