i.e. if Rowling wrote some description about a bigoted neglected single mom striking it rich, and someone else actually wrote the work... than ownership is not guaranteed without legal assignment of rights to said work (depends on the location in the world). Thus, a publisher may not pay the muse unless under legal obligation of rights transfer, and having similar works further complicate exactly who owns the copyrights.
When you publish media or games, than the providence of assets/compositions become extremely important in a commercial setting.
I didn't make the rules, but do hire project artists all the time. The paperwork involved ends up ridiculously complicated, and requires specialized lawyers. This is why we avoid "AI" content, cloud based GPU service, and any vendor ignorant enough to force the issue. =3