But I don't think the artists I'm seeing on Twitter understand that, even in their best case, where training on a copyright image is considered total infringement, this genie still isn't going back in the bottle.
Models are getting better and training more efficient all the time.
Soon you'll be able to train a model entirely on public domain content and have great generative art output.
It might be harder to express the style you want than just sharing a name of an artist in that style, but that won't hold things back.
With this worldview the discussion about whether training on something is infringing its copyright fast becomes irrelevant, for better or worse.