[0] https://developers.google.com/search/docs/crawling-indexing/...
I think Google is probably thinking hard about the problem of training AI: you don't want to train on the output of other AI. That doesn't mean the content shouldn't be processed, just that it shouldn't be used for training. Or maybe it's worth noting that some content is derived from other content that you've manually produced, versus content derived from the content of third parties.
Said another way, I expect that Google isn't just implementing a new allowlist/denylist. It's likely about exposing new information about content.