I could imagine a poorly trained model that returns content nearly identical to original; who would enforce CC rules then?
The bigger issue is when a user uses the model to generate some text. Should they attribute it when using it somewhere?
That doesn't seem very practical, since it seems that soon most of the text will be edited by LLMs and those seem to be trained on most of the web -> so pretty much everything would need to be attributed to everything. Unless someone puts a stop to this, which I find improbable.