> generative art is blindingly obvious.... To me

Have you tested this systematically, or is it possible that you are experiencing survivorship bias? If there were any generative art pieces that you didn't notice, you would have thought that they were human-made. Therefore, all the pieces you identified were "obvious" to you. Not to mention false positives.

I imagine that they haven't done a peer-reviewed scientific study of their ability to notice generative art.

We can replace their statement by "I'm a visual artist and at generative art is often blindingly obvious.... To me....". In other words, they can notice some or most generative art but other people familiar with art can't, or at least can't as often as they do. I think what they are trying to say isn't too changed by that.

Even if it’s obvious to some at this time, as time passes artificially generated writing will become mainstream and what becomes the normal writing style. If you read IX century literature, it reads differently, the vocab is different, the sentences are built differently. It was totally normal back then. It’s not normal now. In ten years the new artificial style will become commonplace and accepted -I mean unless we artificially always make it deviate.