> They didn't copy the texts per-se, they studied the relationships between words to build a statistical/predictive model of natural language.

I understand exactly what you mean by this, and you are wrong. If they did not copy them, it would not be possible to extricate copyrighted works out of the model like Harry Potter. You can argue against the copyright system, but don't pretend that what they've done is essentially an advanced form of copying. The data is in the weights.