This type of reasoning keeps coming up with seemingly zero consideration for why copyright actually exists. The goal of copyright, under US law, is "To promote the progress of science and useful arts".
The goal of companies creating these LLMs is to supersede the use of source material they draw from, like books. You use an LLM because it has all the answers without having to spend the money compensating the original authors, or put in the work digesting it yourself, that's their entire value proposition.
Their end game is to create a product so good that nobody has a reason to ever buy a book again. A few hours after you publish your book, the LLM will gobble it up and distribute the insights contain within to all of their users for free, "it's fair use", they say. There won't be any economic incentive to write books at that point, and so "the progress of science and useful arts" will crawl to a halt. Copyright defeated.
If LLM companies are allowed to produce market substitutes of original works then the goal of copyright is being defeated on a technicality and this ought to be a discussion about whether copyright should be abolished completely, not a discussion about whether big tech should be allowed to get away with it.