I'm not sure it makes sense to assume the creative act of a person writing to other people, which is fundamentally about a consciousness communicating to others, is anything like delivering goods.

The distinction I pointed out, applied to people producing writing intended for other people to read, seems to give a really clear "line". Syntactic tools, you're still fully producing the writing, semantic tools, you're not. You can find some small amount of blurriness if you really want, like does using a thesaurus count as semantic, but it seems disingenuous to pretend that has even close to the same impact on the authorship of the piece as using AI.