That’s a rebuttal on the level of “if a tree falls in the forest and nobody is there to hear it”. Legally, theoretically, you should need permission just as much, but nobody is going to sue you over something nobody else sees.

Copyright addresses reproduction and distribution, paid or not, including derivative works. There are exemptions for journalism and education, AI advanced a lot by using copyrighted materials under the reasoning that it was technological research, but as it spun off into commercial use, its reliance on copyrighted materials for training has become much more questionable.