Read a book, that's fine. Write a book, that's fine. Read a book and then write a book that is 99.9% the same as the book that you read and sell it for profit without a license from the original author, that's infringement.
That's what all these lawsuits are about - it's the training not the reproduction. I already agreed in my first comment that the reproduction is off limits.
In this case, it appears that Meta torrented illegal copies of the work to do the training. Obviously that's bad. But conflating that with training itself doesn't follow.
Pirating content is illegal, regardless of if it is to train an LLM.
Usage of LLMs trained on unlicensed content (basically all of them) might or might not be illegal.
Using any method to reproduce a copyrighted work by using that original as input in a way that supplants the market value of the original is probably illegal.
At least that is my rudimentary understanding.
I don't think anyone thinks that all training is a copyright violation if all the training data is licensed. For example a LLM trained on CC0 content would be fine with basically everyone.
The problem is that training happens on data that is not licensed for that use. Some of that data also is pirated which makes it even clearer that it is illegal.
If you supplant the value of the original with the original as input then you probably have some legal questions to answer.
It's a "rules for thee and not for me" argument.