It isn’t clear to me (other than it’s an open engineering problem) why LLs couldn’t also include attribution as part of training. Also tracking attribution could lead to some insights on how its internal representations in vector space are created.
As an intuition pump, when I write "2+2 = " and you mentally complete it with "4", should I chastise you for not completing it with "4, as per ${your elementary class math textbook} and ${that other book you read as a kid}, corroborated by ${your first math teacher} and ${your parent} quoting ${some other work}"?
It's roughly the same thing.
I.e. in case of both the student and an LLM, correct citation doesn't actually mean the idea originates from the cited work - only that the work contains this idea.