The point is not that devices don't own things but that the owner of the device / creator of the software can't copyright its outputs in his name.

Generating art costs money - electricity to train models and rent/buy the hardware, requires expertise in neural nets, tons of training data from the public domain or privately created, lots of experimenting and fiddling with the parameters, manual curation of the output ...

why should the human who invested all this work not be entitled to the copyright?