Watermarks (spymarks) for AI generated content are important because increasingly we aren't able to tell the difference between real and fake anymore. We will not just increasingly think fake things are real, but also that real things are fake.

Of course, the absence of a watermark/spymark doesn't prove that the source wasn't AI generated. But the absence provides evidence that it wasn't.

AI companies should simply use watermarks in the responsible sense: they should indicate that the material was AI generated, not include personal information in it.